diff --git a/anaconda_project/conda_manager.py b/anaconda_project/conda_manager.py
index 739f690d..b34a6b2f 100644
--- a/anaconda_project/conda_manager.py
+++ b/anaconda_project/conda_manager.py
@@ -442,7 +442,7 @@ def supports_current_platform(self):
         """Whether we have locked deps for the current platform."""
         return self.enabled and conda_api.current_platform() in self.platforms
 
-    def to_json(self):
+    def to_json(self, pkg_key=YamlFile.pkg_key):
         """JSON/YAML version of the lock set."""
         yaml_dict = _CommentedMap()
 
@@ -462,7 +462,7 @@ def to_json(self):
             for package in self._package_specs_by_platform[platform]:
                 packages.append(package)
             packages_dict[platform] = packages
-        yaml_dict[YamlFile.pkg_key] = packages_dict
+        yaml_dict[pkg_key] = packages_dict
 
         _block_style_all_nodes(yaml_dict)
         return yaml_dict
diff --git a/anaconda_project/env_spec.py b/anaconda_project/env_spec.py
index 775008e3..525ef4b0 100644
--- a/anaconda_project/env_spec.py
+++ b/anaconda_project/env_spec.py
@@ -390,10 +390,8 @@ def filter_context(items):
 
         return True
 
-    def to_json(self):
+    def to_json(self, pkg_key=YamlFile.pkg_key):
         """Get JSON for an anaconda-project.yml env spec section."""
-        pkg_key = YamlFile.pkg_key
-
         # Note that we use _conda_packages (only the packages we
         # introduce ourselves) rather than conda_packages
         # (includes inherited packages).
@@ -411,9 +409,9 @@ def to_json(self):
         template_json = ryaml.load("""
 something:
     description: null
-    packages: []
+    <pkg_key>: []
     channels: []
-""".replace('packages', pkg_key),
+""".replace('<pkg_key>', pkg_key),
                                    Loader=ryaml.RoundTripLoader)
 
         if self._description is not None:
diff --git a/anaconda_project/internal/cli/test/test_command_commands.py b/anaconda_project/internal/cli/test/test_command_commands.py
index 79abd361..70d9acfc 100644
--- a/anaconda_project/internal/cli/test/test_command_commands.py
+++ b/anaconda_project/internal/cli/test/test_command_commands.py
@@ -193,7 +193,7 @@ def mock_console_input(prompt):
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: ''}, check_ask_type)
 
 
-def test_add_command_specifying_notebook(monkeypatch, capsys):
+def test_add_command_specifying_notebook(monkeypatch, capsys, pkg_key):
     def check_specifying_notebook(dirname):
         args = Args('notebook', 'test', 'file.ipynb', directory=dirname)
         res = main(args)
@@ -206,11 +206,11 @@ def check_specifying_notebook(dirname):
         assert command['env_spec'] == 'default'
         assert len(command.keys()) == 2
 
-    with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: 'packages:\n - notebook\n'},
+    with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: f'{pkg_key}:\n - notebook\n'},
                                                     check_specifying_notebook)
 
 
-def test_add_command_guessing_notebook(monkeypatch, capsys):
+def test_add_command_guessing_notebook(monkeypatch, capsys, pkg_key):
     def check_guessing_notebook(dirname):
         args = Args(None, 'test', 'file.ipynb', directory=dirname)
         res = main(args)
@@ -225,7 +225,7 @@ def check_guessing_notebook(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: 'packages:\n - notebook\n',
+            DEFAULT_PROJECT_FILENAME: f'{pkg_key}:\n - notebook\n',
             'file.ipynb': "{}"
         }, check_guessing_notebook)
 
@@ -332,7 +332,7 @@ def test_remove_command_with_project_file_problems(capsys, monkeypatch):
                                           append_dir=True)
 
 
-def test_remove_command(monkeypatch, capsys):
+def test_remove_command(monkeypatch, capsys, pkg_key):
     def check(dirname):
         code = _parse_args_and_run_subcommand(['anaconda-project', 'remove-command', 'test', '--directory', dirname])
         assert code == 0
@@ -347,7 +347,7 @@ def check(dirname):
         assert err == ''
 
     with_directory_contents_completing_project_file(
-        {DEFAULT_PROJECT_FILENAME: 'packages: ["notebook"]\ncommands:\n  test:\n    notebook: file.ipynb\n'}, check)
+        {DEFAULT_PROJECT_FILENAME: f'{pkg_key}: ["notebook"]\ncommands:\n  test:\n    notebook: file.ipynb\n'}, check)
 
 
 def test_remove_command_missing(monkeypatch, capsys):
@@ -378,7 +378,7 @@ def check_empty_project(dirname):
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: ""}, check_empty_project)
 
 
-def test_list_commands(capsys):
+def test_list_commands(capsys, pkg_key):
     def check_empty_project(dirname):
         code = _parse_args_and_run_subcommand(['anaconda-project', 'list-commands', '--directory', dirname])
         assert code == 0
@@ -404,13 +404,13 @@ def check_empty_project(dirname):
                                        "    bokeh_app: test.py\n"
                                        "  run_notebook:\n"
                                        "    notebook: test.ipynb\n"
-                                       "packages:\n"
+                                       f"{pkg_key}:\n"
                                        " - bokeh\n"
                                        " - notebook\n")
         }, check_empty_project)
 
 
-def test_list_default_command(capsys):
+def test_list_default_command(capsys, pkg_key):
     def check_empty_project(dirname):
         code = _parse_args_and_run_subcommand(['anaconda-project', 'list-default-command', '--directory', dirname])
         assert code == 0
@@ -426,7 +426,7 @@ def check_empty_project(dirname):
                                        "    bokeh_app: test.py\n"
                                        "  0second:\n"
                                        "    notebook: test.ipynb\n"
-                                       "packages:\n"
+                                       f"{pkg_key}:\n"
                                        " - bokeh\n"
                                        " - notebook\n")
         }, check_empty_project)
diff --git a/anaconda_project/internal/cli/test/test_environment_commands.py b/anaconda_project/internal/cli/test/test_environment_commands.py
index 113db068..a3d30331 100644
--- a/anaconda_project/internal/cli/test/test_environment_commands.py
+++ b/anaconda_project/internal/cli/test/test_environment_commands.py
@@ -164,7 +164,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(dict(), check)
 
 
-def test_remove_env_spec_fails(capsys, monkeypatch):
+def test_remove_env_spec_fails(capsys, monkeypatch, pkg_key):
     def check(dirname):
         from shutil import rmtree as real_rmtree
         _monkeypatch_pwd(monkeypatch, dirname)
@@ -192,13 +192,22 @@ def mock_remove(path, ignore_errors=False, onerror=None):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: 'env_specs:\n  foo:\n    channels: []\n    packages:\n    - bar\n' +
-            '  baz:\n    channels: []\n    packages:\n    - bar\n',
+            DEFAULT_PROJECT_FILENAME: """
+env_specs:
+  foo:
+    channels: []
+    <pkg_key>:
+    - bar
+  baz:
+    channels: []
+    <pkg_key>:
+    - bar
+""".replace('<pkg_key>', pkg_key),
             'envs/foo/bin/test': 'code here'
         }, check)
 
 
-def test_remove_env_spec(capsys, monkeypatch):
+def test_remove_env_spec(capsys, monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_pwd(monkeypatch, dirname)
 
@@ -212,13 +221,22 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: 'env_specs:\n  foo:\n    channels: []\n    packages:\n    - bar\n' +
-            '  bar:\n    channels: []\n    packages:\n    - baz\n',
+            DEFAULT_PROJECT_FILENAME: """
+env_specs:
+  foo:
+    channels: []
+    <pkg_key>:
+    - bar
+  bar:
+    channels: []
+    <pkg_key>:
+    - baz
+""".replace('<pkg_key>', pkg_key),
             'envs/foo/bin/test': 'code here'
         }, check)
 
 
-def test_remove_only_env_spec(capsys, monkeypatch):
+def test_remove_only_env_spec(capsys, monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_pwd(monkeypatch, dirname)
 
@@ -231,12 +249,18 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: 'env_specs:\n  foo:\n    channels: []\n    packages:\n    - bar\n',
+            DEFAULT_PROJECT_FILENAME: """
+env_specs:
+  foo:
+    channels: []
+    <pkg_key>:
+    - bar
+""".replace('<pkg_key>', pkg_key),
             'envs/foo/bin/test': 'code here'
         }, check)
 
 
-def test_remove_env_spec_in_use(capsys, monkeypatch):
+def test_remove_env_spec_in_use(capsys, monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_pwd(monkeypatch, dirname)
 
@@ -258,12 +282,12 @@ def check(dirname):
 
 env_specs:
   other:
-      packages:
+      <pkg_key>:
          - hello
   bar:
-      packages:
+      <pkg_key>:
         - boo
-""",
+""".replace('<pkg_key>', pkg_key),
             'envs/foo/bin/test': 'code here'
         }, check)
 
@@ -278,7 +302,7 @@ def test_remove_env_spec_with_project_file_problems(capsys, monkeypatch):
                                                          ['anaconda-project', 'remove-env-spec', '--name', 'foo'])
 
 
-def test_export_env_spec(capsys, monkeypatch):
+def test_export_env_spec(capsys, monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_pwd(monkeypatch, dirname)
 
@@ -292,13 +316,22 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: 'env_specs:\n  foo:\n    channels: []\n    packages:\n    - bar\n' +
-            '  bar:\n    channels: []\n    packages:\n    - baz\n',
+            DEFAULT_PROJECT_FILENAME: """
+env_specs:
+  foo:
+    channels: []
+    <pkg_key>:
+    - bar
+  bar:
+    channels: []
+    <pkg_key>:
+    - baz
+""".replace('<pkg_key>', pkg_key),
             'envs/foo/bin/test': 'code here'
         }, check)
 
 
-def test_export_env_spec_default_name(capsys, monkeypatch):
+def test_export_env_spec_default_name(capsys, monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_pwd(monkeypatch, dirname)
 
@@ -312,13 +345,22 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: 'env_specs:\n  foo:\n    channels: []\n    packages:\n    - bar\n' +
-            '  bar:\n    channels: []\n    packages:\n    - baz\n',
+            DEFAULT_PROJECT_FILENAME: """
+env_specs:
+  foo:
+    channels: []
+    <pkg_key>:
+    - bar
+  bar:
+    channels: []
+    <pkg_key>:
+    - baz
+""".replace('<pkg_key>', pkg_key),
             'envs/foo/bin/test': 'code here'
         }, check)
 
 
-def test_export_env_spec_no_filename(capsys, monkeypatch):
+def test_export_env_spec_no_filename(capsys, monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_pwd(monkeypatch, dirname)
 
@@ -331,8 +373,17 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: 'env_specs:\n  foo:\n    channels: []\n    packages:\n    - bar\n' +
-            '  bar:\n    channels: []\n    packages:\n    - baz\n',
+            DEFAULT_PROJECT_FILENAME: """
+env_specs:
+  foo:
+    channels: []
+    <pkg_key>:
+    - bar
+  bar:
+    channels: []
+    <pkg_key>:
+    - baz
+""".replace('<pkg_key>', pkg_key),
             'envs/foo/bin/test': 'code here'
         }, check)
 
@@ -384,7 +435,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(dict(), check)
 
 
-def test_add_packages_to_specific_environment(capsys, monkeypatch):
+def test_add_packages_to_specific_environment(capsys, monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_pwd(monkeypatch, dirname)
         params = _monkeypatch_add_packages(monkeypatch, SimpleStatus(success=True, description='Installed ok.'))
@@ -404,9 +455,9 @@ def check(dirname):
         {DEFAULT_PROJECT_FILENAME: """
 env_specs:
   foo:
-   packages:
+   <pkg_key>:
      - bar
-"""}, check)
+""".replace('<pkg_key>', pkg_key)}, check)
 
 
 def test_add_pip_packages_to_specific_environment(capsys, monkeypatch):
@@ -426,12 +477,14 @@ def check(dirname):
         assert dict(env_spec_name='foo', packages=['a', 'b'], channels=None, pip=True) == params['kwargs']
 
     with_directory_contents_completing_project_file(
-        {DEFAULT_PROJECT_FILENAME: """
+        {
+            DEFAULT_PROJECT_FILENAME: """
 env_specs:
   foo:
-   packages:
+   <pkg_key>:
      - bar
-"""}, check)
+"""
+        }, check)
 
 
 def test_remove_packages_from_all_environments(capsys, monkeypatch):
@@ -498,7 +551,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(dict(), check)
 
 
-def test_add_platforms_to_specific_environment(capsys, monkeypatch):
+def test_add_platforms_to_specific_environment(capsys, monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_pwd(monkeypatch, dirname)
         params = _monkeypatch_add_platforms(monkeypatch, SimpleStatus(success=True, description='Installed ok.'))
@@ -514,12 +567,14 @@ def check(dirname):
         assert dict(env_spec_name='foo', platforms=['a', 'b']) == params['kwargs']
 
     with_directory_contents_completing_project_file(
-        {DEFAULT_PROJECT_FILENAME: """
+        {
+            DEFAULT_PROJECT_FILENAME: """
 env_specs:
   foo:
-   packages:
+   <pkg_key>:
      - bar
-"""}, check)
+""".replace('<pkg_key>', pkg_key)
+        }, check)
 
 
 def test_remove_platforms_from_all_environments(capsys, monkeypatch):
@@ -558,7 +613,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(dict(), check)
 
 
-def test_list_environments(capsys, monkeypatch):
+def test_list_environments(capsys, monkeypatch, pkg_key):
     def check_list_not_empty(dirname):
         code = _parse_args_and_run_subcommand(['anaconda-project', 'list-env-specs', '--directory', dirname])
 
@@ -577,13 +632,15 @@ def check_list_not_empty(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: ('env_specs:\n'
-                                       '  foo:\n'
-                                       '    packages:\n'
-                                       '      - bar\n'
-                                       '  bar:\n'
-                                       '    packages:\n'
-                                       '      - bar\n')
+            DEFAULT_PROJECT_FILENAME: """
+env_specs:
+  foo:
+    <pkg_key>:
+      - bar
+  bar:
+    <pkg_key>:
+      - bar
+""".replace('<pkg_key>', pkg_key)
         }, check_list_not_empty)
 
 
@@ -629,7 +686,7 @@ def check_missing_env(dirname):
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: ""}, check_missing_env)
 
 
-def _test_list_packages(capsys, env, expected_conda_deps, expected_pip_deps):
+def _test_list_packages(capsys, env, expected_conda_deps, expected_pip_deps, pkg_key):
     def check_list_not_empty(dirname):
         params = ['anaconda-project', 'list-packages', '--directory', dirname]
         if env is not None:
@@ -648,30 +705,34 @@ def check_list_not_empty(dirname):
                                                                         expected_pip_deps)
         assert out == expected_out
 
-    project_contents = ('env_specs:\n'
-                        '  foo:\n'
-                        '    packages:\n'
-                        '      - requests\n'
-                        '      - flask\n'
-                        '  bar:\n'
-                        '    packages:\n'
-                        '      - httplib\n'
-                        '      - django\n\n'
-                        'packages:\n'
-                        ' - mandatory_package\n'
-                        ' - pip:\n'
-                        '     - mandatory_pip_package\n')
+    project_contents = """
+env_specs:
+  foo:
+    <pkg_key>:
+      - requests
+      - flask
+  bar:
+    <pkg_key>:
+      - httplib
+      - django\n
+<pkg_key>:
+ - mandatory_package
+ - pip:
+     - mandatory_pip_package""".replace('<pkg_key>', pkg_key)
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: project_contents}, check_list_not_empty)
 
 
-def test_list_packages_from_env(capsys):
-    _test_list_packages(capsys, 'bar', '\ndjango\nhttplib\nmandatory_package\n\n', '\nmandatory_pip_package\n\n')
-    _test_list_packages(capsys, 'foo', '\nflask\nmandatory_package\nrequests\n\n', '\nmandatory_pip_package\n\n')
+def test_list_packages_from_env(capsys, pkg_key):
+    _test_list_packages(capsys, 'bar', '\ndjango\nhttplib\nmandatory_package\n\n',
+                        '\nmandatory_pip_package\n\n', pkg_key=pkg_key)
+    _test_list_packages(capsys, 'foo', '\nflask\nmandatory_package\nrequests\n\n',
+                        '\nmandatory_pip_package\n\n', pkg_key=pkg_key)
 
 
-def test_list_packages_from_env_default(capsys):
-    _test_list_packages(capsys, None, '\nflask\nmandatory_package\nrequests\n\n', '\nmandatory_pip_package\n\n')
+def test_list_packages_from_env_default(capsys, pkg_key):
+    _test_list_packages(capsys, None, '\nflask\nmandatory_package\nrequests\n\n',
+                        '\nmandatory_pip_package\n\n', pkg_key=pkg_key)
 
 
 def test_list_packages_with_project_file_problems(capsys, monkeypatch):
diff --git a/anaconda_project/internal/cli/test/test_prepare.py b/anaconda_project/internal/cli/test/test_prepare.py
index d11e6ca5..fd998fe2 100644
--- a/anaconda_project/internal/cli/test/test_prepare.py
+++ b/anaconda_project/internal/cli/test/test_prepare.py
@@ -116,7 +116,8 @@ def main_redis_url(dirname):
     assert "All ports from 6380 to 6449 were in use" in err
 
 
-def test_prepare_command_choose_environment(capsys, monkeypatch):
+#@pytest._change_default_pkg_key
+def test_prepare_command_choose_environment(capsys, monkeypatch, pkg_key):
     def mock_conda_create(prefix, pkgs, channels, stdout_callback, stderr_callback):
         from anaconda_project.internal.makedirs import makedirs_ok_if_exists
         metadir = os.path.join(prefix, "conda-meta")
@@ -142,16 +143,15 @@ def check_prepare_choose_environment(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME:
-            """
+            DEFAULT_PROJECT_FILENAME: """
 env_specs:
   foo:
-    packages:
+    <pkg_key>:
         - nonexistent_foo
   bar:
-    packages:
+    <pkg_key>:
         - nonexistent_bar
-"""
+""".replace("<pkg_key>", pkg_key)
         }, check_prepare_choose_environment)
 
     out, err = capsys.readouterr()
@@ -160,7 +160,7 @@ def check_prepare_choose_environment(dirname):
     assert err == ""
 
 
-def test_prepare_command_all_environments(capsys, monkeypatch):
+def test_prepare_command_all_environments(capsys, monkeypatch, pkg_key):
     def mock_conda_create(prefix, pkgs, channels, stdout_callback, stderr_callback):
         from anaconda_project.internal.makedirs import makedirs_ok_if_exists
         metadir = os.path.join(prefix, "conda-meta")
@@ -188,16 +188,15 @@ def check_prepare_choose_environment(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME:
-            """
+            DEFAULT_PROJECT_FILENAME: """
 env_specs:
   foo:
-    packages:
+    <pkg_key>:
         - nonexistent_foo
   bar:
-    packages:
+    <pkg_key>:
         - nonexistent_bar
-"""
+""".replace("<pkg_key>", pkg_key)
         }, check_prepare_choose_environment)
 
     out, err = capsys.readouterr()
@@ -206,7 +205,7 @@ def check_prepare_choose_environment(dirname):
     assert err == ""
 
 
-def test_prepare_command_all_environments_refresh(capsys, monkeypatch):
+def test_prepare_command_all_environments_refresh(capsys, monkeypatch, pkg_key):
     def mock_conda_create(prefix, pkgs, channels, stdout_callback, stderr_callback):
         from anaconda_project.internal.makedirs import makedirs_ok_if_exists
         metadir = os.path.join(prefix, "conda-meta")
@@ -238,16 +237,15 @@ def check_prepare_choose_environment(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME:
-            """
+            DEFAULT_PROJECT_FILENAME: """
 env_specs:
   foo:
-    packages:
+    <pkg_key>:
         - nonexistent_foo
   bar:
-    packages:
+    <pkg_key>:
         - nonexistent_bar
-"""
+""".replace("<pkg_key>", pkg_key)
         }, check_prepare_choose_environment)
 
     out, err = capsys.readouterr()
@@ -258,7 +256,7 @@ def check_prepare_choose_environment(dirname):
     assert err == ""
 
 
-def test_prepare_command_default_environment_refresh(capsys, monkeypatch):
+def test_prepare_command_default_environment_refresh(capsys, monkeypatch, pkg_key):
     def mock_conda_create(prefix, pkgs, channels, stdout_callback, stderr_callback):
         from anaconda_project.internal.makedirs import makedirs_ok_if_exists
         metadir = os.path.join(prefix, "conda-meta")
@@ -285,9 +283,9 @@ def check_prepare_choose_environment(dirname):
         assert os.path.isfile(foo_package_json)
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
     - nonexistent_foo
-"""}, check_prepare_choose_environment)
+""".replace("<pkg_key>", pkg_key)}, check_prepare_choose_environment)
 
     out, err = capsys.readouterr()
     assert out == ("The project is ready to run commands.\n" +
@@ -297,7 +295,7 @@ def check_prepare_choose_environment(dirname):
     assert err == ""
 
 
-def test_prepare_command_choose_environment_does_not_exist(capsys):
+def test_prepare_command_choose_environment_does_not_exist(capsys, pkg_key):
     def check_prepare_choose_environment_does_not_exist(dirname):
         project_dir_disable_dedicated_env(dirname)
         result = _parse_args_and_run_subcommand(
@@ -312,21 +310,20 @@ def check_prepare_choose_environment_does_not_exist(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME:
-            """
+            DEFAULT_PROJECT_FILENAME: """
 env_specs:
   foo:
-    packages:
+    <pkg_key>:
         - nonexistent_foo
   bar:
-    packages:
+    <pkg_key>:
         - nonexistent_bar
-"""
+""".replace("<pkg_key>", pkg_key)
         }, check_prepare_choose_environment_does_not_exist)
 
 
 @pytest.mark.slow
-def test_prepare_command_choose_command_chooses_env_spec(capsys):
+def test_prepare_command_choose_command_chooses_env_spec(capsys, pkg_key):
     def check(dirname):
         project_dir_disable_dedicated_env(dirname)
         result = _parse_args_and_run_subcommand(
@@ -347,14 +344,13 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME:
-            """
+            DEFAULT_PROJECT_FILENAME: """
 env_specs:
   foo:
-    packages:
+    <pkg_key>:
         - nonexistent_foo
   bar:
-    packages:
+    <pkg_key>:
         - nonexistent_bar
 commands:
   with_foo:
@@ -364,7 +360,7 @@ def check(dirname):
     conda_app_entry: python --version
     env_spec: bar
 
-"""
+""".replace("<pkg_key>", pkg_key)
         }, check)
 
 
@@ -605,7 +601,7 @@ def mock_console_input(prompt, encrypted):
 
 
 @pytest.mark.slow
-def test_no_ask_conda_prefix_interactively(monkeypatch, capsys):
+def test_no_ask_conda_prefix_interactively(monkeypatch, capsys, pkg_key):
     def check(dirname):
         project_dir_disable_dedicated_env(dirname)
 
@@ -628,12 +624,12 @@ def mock_console_input(prompt, encrypted):
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
  - nonexistent_package_name
-"""}, check)
+""".replace("<pkg_key>", pkg_key)}, check)
 
 
-def test_display_suggestions(monkeypatch, capsys):
+def test_display_suggestions(monkeypatch, capsys, pkg_key):
     def check(dirname):
         project_dir_disable_dedicated_env(dirname)
 
@@ -661,6 +657,6 @@ def mock_console_input(prompt, encrypted):
         assert '' == err
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: """
-packages: []
+<pkg_key>: []
 weird_field: 42
-"""}, check)
+""".replace("<pkg_key>", pkg_key)}, check)
diff --git a/anaconda_project/project.py b/anaconda_project/project.py
index 050a5fba..abeb987c 100644
--- a/anaconda_project/project.py
+++ b/anaconda_project/project.py
@@ -841,7 +841,8 @@ def set_env_spec_platforms(project):
                 prompt = "Overwrite env spec %s with the changes from %s?" % (importable_spec.name, importable_filename)
 
             def overwrite_env_spec_from_importable(project):
-                project.project_file.set_value(['env_specs', importable_spec.name], importable_spec.to_json())
+                project.project_file.set_value(['env_specs', importable_spec.name],
+                                               importable_spec.to_json(pkg_key=project.pkg_key))
 
             def remember_no_import_importable(project):
                 project.project_file.set_value(['skip_imports', 'environment'], importable_spec.logical_hash)
@@ -862,7 +863,8 @@ def remember_no_import_importable(project):
             # import, above.
             def add_default_env_spec(project):
                 default_spec = _anaconda_default_env_spec(self.global_base_env_spec)
-                project.project_file.set_value(['env_specs', default_spec.name], default_spec.to_json())
+                project.project_file.set_value(['env_specs', default_spec.name],
+                                               default_spec.to_json(pkg_key=project.pkg_key))
 
             # This section should now be inaccessible
             # since env_spec will be added at runtime if missing
@@ -1202,6 +1204,10 @@ def load_default_specs():
         assert isinstance(frontend, Frontend)
         self._frontends = [frontend]
 
+    @property
+    def pkg_key(self):
+        return self.project_file.pkg_key
+    
     def _updated_cache(self):
         self._config_cache.update(self._project_file, self._lock_file)
         return self._config_cache
diff --git a/anaconda_project/project_file.py b/anaconda_project/project_file.py
index 9cac5880..aee485fe 100644
--- a/anaconda_project/project_file.py
+++ b/anaconda_project/project_file.py
@@ -92,7 +92,7 @@ class ProjectFile(YamlFile):
 # before your code runs.
 # Use `anaconda-project add-packages` to add packages.
 #
-packages: []
+<pkg_key>: []
 
 #
 # In the channels section, list any Conda channel URLs to be searched
@@ -119,7 +119,7 @@ class ProjectFile(YamlFile):
 # Use `anaconda-project add-env-spec` to add environment specs.
 #
 env_specs: {}
-'''
+'''.replace('<pkg_key>', YamlFile.pkg_key)
 
     @classmethod
     def load_for_directory(cls, directory, default_env_specs_func=_empty_default_env_spec, scan_parents=True):
@@ -190,7 +190,7 @@ def _fill_default_content(self, as_json):
         default_env_specs = self._default_env_specs_func()
         assert default_env_specs is not None
         for env_spec in default_env_specs:
-            as_json['env_specs'][env_spec.name] = env_spec.to_json()
+            as_json['env_specs'][env_spec.name] = env_spec.to_json(pkg_key=self.pkg_key)
 
         if len(default_env_specs) == 1:
             # if there's only one env spec, keep it for name/description
@@ -204,8 +204,8 @@ def move_list_elements(src, dest):
                 dest.extend(src)
                 del src[:]
 
-            if 'packages' in spec_json:
-                move_list_elements(spec_json['packages'], as_json['packages'])
+            if self.pkg_key in spec_json:
+                move_list_elements(spec_json[self.pkg_key], as_json[self.pkg_key])
             if 'channels' in spec_json:
                 move_list_elements(spec_json['channels'], as_json['channels'])
             if 'platforms' in spec_json:
diff --git a/anaconda_project/project_lock_file.py b/anaconda_project/project_lock_file.py
index e1197240..39fc3c45 100644
--- a/anaconda_project/project_lock_file.py
+++ b/anaconda_project/project_lock_file.py
@@ -136,7 +136,7 @@ def _set_lock_set(self, env_spec_name, lock_set, all_names):
                 single_env['locked'] = False
 
         # now set up the one env
-        as_json = lock_set.to_json()
+        as_json = lock_set.to_json(pkg_key=self.pkg_key)
         self.set_value(['env_specs', env_spec_name], as_json)
 
     def _add_pip_packages(self, env_spec_name, pip_packages):
diff --git a/anaconda_project/requirements_registry/providers/test/test_conda_env.py b/anaconda_project/requirements_registry/providers/test/test_conda_env.py
index 1f57e7d4..707b8ac1 100644
--- a/anaconda_project/requirements_registry/providers/test/test_conda_env.py
+++ b/anaconda_project/requirements_registry/providers/test/test_conda_env.py
@@ -178,7 +178,7 @@ def prepare_project_scoped_env_not_attempted(dirname):
 
 
 @pytest.mark.slow
-def test_prepare_project_scoped_env_with_packages(monkeypatch):
+def test_prepare_project_scoped_env_with_packages(monkeypatch, pkg_key):
     monkeypatch_conda_not_to_use_links(monkeypatch)
 
     def prepare_project_scoped_env_with_packages(dirname):
@@ -222,16 +222,15 @@ def prepare_project_scoped_env_with_packages(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME:
-            """
-packages:
+            DEFAULT_PROJECT_FILENAME: """
+<pkg_key>:
     - python=3.7
     - ipython
     - numpy=1.15
     - pip
     - pip:
       - flake8
-"""
+""".replace('<pkg_key>', pkg_key)
         }, prepare_project_scoped_env_with_packages)
 
 
@@ -301,7 +300,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(dict(), check)
 
 
-def test_configure_different_env_spec(monkeypatch):
+def test_configure_different_env_spec(monkeypatch, pkg_key):
     def mock_conda_create(prefix, pkgs, channels, stdout_callback, stderr_callback):
         from anaconda_project.internal.makedirs import makedirs_ok_if_exists
         metadir = os.path.join(prefix, "conda-meta")
@@ -342,19 +341,18 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME:
-            """
+            DEFAULT_PROJECT_FILENAME: """
 env_specs:
   default:
-    packages: []
+    <pkg_key>: []
     channels: []
   foo:
-    packages: []
+    <pkg_key>: []
     channels: []
   bar:
-    packages: []
+    <pkg_key>: []
     channels: []
-"""
+""".replace('<pkg_key>', pkg_key)
         }, check)
 
 
@@ -378,7 +376,7 @@ def _readonly_env(env_name, packages):
 
 @pytest.mark.slow
 @pytest.mark.skipif(platform.system() == 'Windows', reason='Windows has a hard time with read-only directories')
-def test_clone_readonly_environment_with_deviations(monkeypatch):
+def test_clone_readonly_environment_with_deviations(monkeypatch, pkg_key):
     def clone_readonly_and_prepare(dirname):
         with _readonly_env(env_name='default', packages=('python=3.7', )) as ro_prefix:
             readonly = conda_api.installed(ro_prefix)
@@ -403,17 +401,17 @@ def clone_readonly_and_prepare(dirname):
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
   - python=3.7
   - requests
 env_specs:
   default: {}
-"""}, clone_readonly_and_prepare)
+""".replace('<pkg_key>', pkg_key)}, clone_readonly_and_prepare)
 
 
 @pytest.mark.slow
 @pytest.mark.skipif(platform.system() == 'Windows', reason='Windows has a hard time with read-only directories')
-def test_replace_readonly_environment_with_deviations(monkeypatch):
+def test_replace_readonly_environment_with_deviations(monkeypatch, pkg_key):
     def replace_readonly_and_prepare(dirname):
         with _readonly_env(env_name='default', packages=('python=3.7', )) as ro_prefix:
             readonly = conda_api.installed(ro_prefix)
@@ -438,17 +436,17 @@ def replace_readonly_and_prepare(dirname):
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
   - python=3.7
   - requests
 env_specs:
   default: {}
-"""}, replace_readonly_and_prepare)
+""".replace('<pkg_key>', pkg_key)}, replace_readonly_and_prepare)
 
 
 @pytest.mark.slow
 @pytest.mark.skipif(platform.system() == 'Windows', reason='Windows has a hard time with read-only directories')
-def test_fail_readonly_environment_with_deviations_unset_policy(monkeypatch):
+def test_fail_readonly_environment_with_deviations_unset_policy(monkeypatch, pkg_key):
     def clone_readonly_and_prepare(dirname):
         with _readonly_env(env_name='default', packages=('python=3.7', )) as ro_prefix:
             readonly = conda_api.installed(ro_prefix)
@@ -466,17 +464,17 @@ def clone_readonly_and_prepare(dirname):
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
   - python=3.7
   - requests
 env_specs:
   default: {}
-"""}, clone_readonly_and_prepare)
+""".replace('<pkg_key>', pkg_key)}, clone_readonly_and_prepare)
 
 
 @pytest.mark.slow
 @pytest.mark.skipif(platform.system() == 'Windows', reason='Windows has a hard time with read-only directories')
-def test_fail_readonly_environment_with_deviations_set_policy(monkeypatch):
+def test_fail_readonly_environment_with_deviations_set_policy(monkeypatch, pkg_key):
     def clone_readonly_and_prepare(dirname):
         with _readonly_env(env_name='default', packages=('python=3.7', )) as ro_prefix:
             readonly = conda_api.installed(ro_prefix)
@@ -496,9 +494,9 @@ def clone_readonly_and_prepare(dirname):
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
   - python=3.7
   - requests
 env_specs:
   default: {}
-"""}, clone_readonly_and_prepare)
+""".replace('<pkg_key>', pkg_key)}, clone_readonly_and_prepare)
diff --git a/anaconda_project/test/test_env_spec.py b/anaconda_project/test/test_env_spec.py
index 2e2fa1c9..ad1e8386 100644
--- a/anaconda_project/test/test_env_spec.py
+++ b/anaconda_project/test/test_env_spec.py
@@ -250,7 +250,7 @@ def test_find_out_of_sync_does_not_exist():
     assert name is None
 
 
-def test_to_json():
+def test_to_json(pkg_key):
     # the stuff from this parent env spec should NOT end up in the JSON
     hi = EnvSpec(name="hi",
                  conda_packages=['q', 'r'],
@@ -265,19 +265,19 @@ def test_to_json():
                    channels=['x', 'y'],
                    inherit_from_names=('hi', ),
                    inherit_from=(hi, ))
-    json = spec.to_json()
+    json = spec.to_json(pkg_key=pkg_key)
 
     assert {
         'description': "The Foo Spec",
         'channels': ['x', 'y'],
         'inherit_from': 'hi',
-        'packages': ['a', 'b', {
+        pkg_key: ['a', 'b', {
             'pip': ['c', 'd']
         }]
     } == json
 
 
-def test_to_json_no_description_no_pip_no_inherit():
+def test_to_json_no_description_no_pip_no_inherit(pkg_key):
     # should be able to jsonify a spec with no description
     spec = EnvSpec(name="foo",
                    conda_packages=['a', 'b'],
@@ -285,23 +285,23 @@ def test_to_json_no_description_no_pip_no_inherit():
                    channels=['x', 'y'],
                    inherit_from_names=(),
                    inherit_from=())
-    json = spec.to_json()
+    json = spec.to_json(pkg_key=pkg_key)
 
-    assert {'channels': ['x', 'y'], 'packages': ['a', 'b']} == json
+    assert {'channels': ['x', 'y'], pkg_key: ['a', 'b']} == json
 
 
-def test_to_json_multiple_inheritance():
+def test_to_json_multiple_inheritance(pkg_key):
     spec = EnvSpec(name="foo",
                    conda_packages=['a', 'b'],
                    pip_packages=['c', 'd'],
                    channels=['x', 'y'],
                    inherit_from_names=('hi', 'hello'))
-    json = spec.to_json()
+    json = spec.to_json(pkg_key=pkg_key)
 
     assert {
         'channels': ['x', 'y'],
         'inherit_from': ['hi', 'hello'],
-        'packages': ['a', 'b', {
+        pkg_key: ['a', 'b', {
             'pip': ['c', 'd']
         }]
     } == json
diff --git a/anaconda_project/test/test_project.py b/anaconda_project/test/test_project.py
index 6e541371..17fffb80 100644
--- a/anaconda_project/test/test_project.py
+++ b/anaconda_project/test/test_project.py
@@ -241,7 +241,7 @@ def check_problem(dirname):
 """}, check_problem)
 
 
-def test_problem_empty_names(packages):
+def test_problem_empty_names(pkg_key):
     def check_problem(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -265,7 +265,7 @@ def _fn(s):
   ' ': redis
 env_specs:
   ' ':
-    {packages}:
+    {pkg_key}:
        - python
 commands:
   ' ':
@@ -473,7 +473,7 @@ def check_set_icon(dirname):
         }, check_set_icon)
 
 
-def test_get_package_requirements_from_project_file(packages):
+def test_get_package_requirements_from_project_file(pkg_key):
     def check_get_packages(dirname):
         project = project_no_dedicated_env(dirname)
         env = project.env_specs['default']
@@ -499,7 +499,7 @@ def check_get_packages(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   - foo
   - hello >= 1.0
   - world
@@ -524,31 +524,31 @@ def check_get_packages(dirname):
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: ""}, check_get_packages)
 
 
-def test_complain_about_packages_not_a_list(packages):
+def test_complain_about_packages_not_a_list(pkg_key):
     def check_get_packages(dirname):
         project = project_no_dedicated_env(dirname)
         assert 1 == len(project.problems)
         "should be a list of strings not" in project.problems[0]
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
     foo: bar
     """}, check_get_packages)
 
 
-def test_complain_about_pip_deps_not_a_list(packages):
+def test_complain_about_pip_deps_not_a_list(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert 1 == len(project.problems)
         "should be a list of strings not" in project.problems[0]
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
     - pip: bar
     """}, check)
 
 
-def test_complain_about_pip_deps_not_a_string(packages):
+def test_complain_about_pip_deps_not_a_string(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert 1 == len(project.problems)
@@ -556,13 +556,13 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
     - pip:
       - {}
-    """.replace('packages', packages)}, check)
+    """.replace('<pkg_key>', pkg_key)}, check)
 
 
-def test_complain_about_packages_bad_spec(packages):
+def test_complain_about_packages_bad_spec(pkg_key):
     def check_get_packages(dirname):
         project = project_no_dedicated_env(dirname)
         filename = project.project_file.basename
@@ -574,7 +574,7 @@ def check_get_packages(dirname):
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
     - "="
     - foo bar
     - pip:
@@ -619,7 +619,7 @@ def check_complain_about_conda_env_var(dirname):
 
 
 @pytest._change_default_pkg_key
-def test_load_environments(packages):
+def test_load_environments(pkg_key):
     def check_environments(dirname):
         project = project_no_dedicated_env(dirname)
         assert 0 == len(project.problems)
@@ -688,7 +688,7 @@ def check_environments(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
   - global1=1.0
   - global2=1.0
 channels:
@@ -697,7 +697,7 @@ def check_environments(dirname):
 env_specs:
   foo:
     description: "THE FOO"
-    packages:
+    <pkg_key>:
        - python
        - dog
        - cat
@@ -705,7 +705,7 @@ def check_environments(dirname):
   bar: {}
   foo_child:
     inherit_from: foo
-    packages:
+    <pkg_key>:
        - dog=2.0
        - global1=2.0
        - lion
@@ -714,7 +714,7 @@ def check_environments(dirname):
     channels:
        - abc
   mixin:
-    packages:
+    <pkg_key>:
        - bunny
        - walrus=1.0
        - global2=2.0
@@ -724,18 +724,18 @@ def check_environments(dirname):
        - hbo
   foo_grandchild:
     inherit_from: [foo_child, mixin]
-    packages:
+    <pkg_key>:
        - walrus=2.0
        - dog=3.0
        - pip:
          - seahorse
     channels:
        - nbc
-    """.replace('packages', packages)
+    """.replace('<pkg_key>', pkg_key)
         }, check_environments)
 
 
-def test_load_environments_merging_in_global(packages):
+def test_load_environments_merging_in_global(pkg_key):
     def check_environments(dirname):
         project = project_no_dedicated_env(dirname)
         assert 0 == len(project.problems)
@@ -757,7 +757,7 @@ def check_environments(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: """
-packages:
+<pkg_key>:
   - dead-parrot
   - elephant
 
@@ -766,7 +766,7 @@ def check_environments(dirname):
 
 env_specs:
   foo:
-    packages:
+    <pkg_key>:
        - python
        - dog
        - cat
@@ -775,11 +775,11 @@ def check_environments(dirname):
        - hbo
   bar: {}
   default:
-    packages:
+    <pkg_key>:
       - lion
     channels:
       - cartoons
-    """.replace('packages', packages)
+    """.replace('<pkg_key>', pkg_key)
         }, check_environments)
 
 
@@ -847,14 +847,14 @@ def check_environments(dirname):
     """}, check_environments)
 
 
-def test_complain_about_packages_list_of_wrong_thing(packages):
+def test_complain_about_packages_list_of_wrong_thing(pkg_key):
     def check_get_packages(dirname):
         project = project_no_dedicated_env(dirname)
         assert 1 == len(project.problems)
         "should be a string not '42'" in project.problems[0]
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
     - 42
     """}, check_get_packages)
 
@@ -1196,7 +1196,7 @@ def check(dirname):
         check)
 
 
-def test_command_with_custom_description(packages):
+def test_command_with_custom_description(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
@@ -1207,7 +1207,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME:
-            f"commands:\n default:\n    bokeh_app: test.py\n    description: hi\n{packages}:\n - bokeh\n"
+            f"commands:\n default:\n    bokeh_app: test.py\n    description: hi\n{pkg_key}:\n - bokeh\n"
         }, check)
 
 
@@ -1585,7 +1585,7 @@ def check(dirname):
         {DEFAULT_PROJECT_FILENAME: "commands:\n default:\n    notebook: test.ipynb\n"}, check)
 
 
-def test_notebook_guess_command(packages):
+def test_notebook_guess_command(pkg_key):
     def check_notebook_guess_command(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -1616,7 +1616,7 @@ def check_notebook_guess_command(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME:
-            f"commands:\n default:\n    unix: echo 'pass'\nservices:\n    REDIS_URL: redis\n{packages}: ['notebook']\n",
+            f"commands:\n default:\n    unix: echo 'pass'\nservices:\n    REDIS_URL: redis\n{pkg_key}: ['notebook']\n",
             'test.ipynb': '{}',
             'envs/should_ignore_this.ipynb': '{}',
             'services/should_ignore_this.ipynb': '{}',
@@ -1627,7 +1627,7 @@ def check_notebook_guess_command(dirname):
     # anaconda-project run data.ipynb
 
 
-def test_notebook_guess_command_can_be_default(packages):
+def test_notebook_guess_command_can_be_default(pkg_key):
     def check_notebook_guess_command_can_be_default(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -1648,7 +1648,7 @@ def check_notebook_guess_command_can_be_default(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: f"{packages}: ['notebook']\n",
+            DEFAULT_PROJECT_FILENAME: f"{pkg_key}: ['notebook']\n",
             # we pick the first command alphabetically in this case
             # so the test looks for that
             'a.ipynb': '{}',
@@ -1685,7 +1685,7 @@ def mock_find_executable(*args, **kwargs):
         {DEFAULT_PROJECT_FILENAME: "commands:\n default:\n    notebook: test.ipynb\n"}, check_notebook_command)
 
 
-def test_multiple_notebooks_suggestion_rejected(packages):
+def test_multiple_notebooks_suggestion_rejected(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -1709,7 +1709,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME:
-            f"commands:\n default:\n    unix: echo 'pass'\nservices:\n    REDIS_URL: redis\n{packages}: ['notebook']\n",
+            f"commands:\n default:\n    unix: echo 'pass'\nservices:\n    REDIS_URL: redis\n{pkg_key}: ['notebook']\n",
             'test.ipynb': '{}',
             'foo/test2.ipynb': '{}',
             'envs/should_ignore_this.ipynb': 'pretend this is more notebook data',
@@ -1719,7 +1719,7 @@ def check(dirname):
         }, check)
 
 
-def test_skip_all_notebook_imports(packages):
+def test_skip_all_notebook_imports(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -1735,12 +1735,12 @@ def check(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME:
-            f"commands:\n default:\n    unix: echo 'pass'\nservices:\n    REDIS_URL: redis\n{packages}: ['notebook']\n",
+            f"commands:\n default:\n    unix: echo 'pass'\nservices:\n    REDIS_URL: redis\n{pkg_key}: ['notebook']\n",
             'test.ipynb': '{}'
         }, check)
 
 
-def test_invalid_skip_imports_notebooks(packages):
+def test_invalid_skip_imports_notebooks(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert 1 == len(project.problems)
@@ -1755,14 +1755,14 @@ def check(dirname):
     unix: echo 'pass'
 services:
     REDIS_URL: redis
-packages: ['notebook']
+<pkg_key>: ['notebook']
 skip_imports:
   notebooks: {}
-""".replace('packages', packages)
+""".replace('<pkg_key>', pkg_key)
         }, check)
 
 
-def test_single_notebook_suggestion_rejected(packages):
+def test_single_notebook_suggestion_rejected(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -1784,7 +1784,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME:
-            f"commands:\n default:\n    unix: echo 'pass'\nservices:\n    REDIS_URL: redis\n{packages}: ['notebook']\n",
+            f"commands:\n default:\n    unix: echo 'pass'\nservices:\n    REDIS_URL: redis\n{pkg_key}: ['notebook']\n",
             'test.ipynb': '{}',
             'envs/should_ignore_this.ipynb': 'pretend this is more notebook data',
             'services/should_ignore_this.ipynb': 'pretend this is more notebook data',
@@ -2320,7 +2320,7 @@ def check_run_with_stuff_missing(dirname):
 
 
 @pytest._change_default_pkg_key
-def test_get_publication_info_from_empty_project(packages):
+def test_get_publication_info_from_empty_project(pkg_key):
     def check_publication_info_from_empty(dirname):
         project = project_no_dedicated_env(dirname)
         expected = {
@@ -2332,7 +2332,7 @@ def check_publication_info_from_empty(dirname):
             'env_specs': {
                 'default': {
                     'channels': [],
-                    packages: [],
+                    pkg_key: [],
                     'description': 'Default',
                     'locked': False,
                     'platforms': [],
@@ -2373,7 +2373,7 @@ def check_publication_info_from_empty(dirname):
     notebook: foo.ipynb
     registers_fusion_function: true
 
-packages:
+<pkg_key>:
   - foo
 
 channels:
@@ -2382,17 +2382,17 @@ def check_publication_info_from_empty(dirname):
 env_specs:
   default:
     description: "Default"
-    packages:
+    <pkg_key>:
       - notebook
   woot:
-    packages:
+    <pkg_key>:
       - blah
       - bokeh
     channels:
       - woohoo
   w00t:
     description: "double 0"
-    packages:
+    <pkg_key>:
       - something
   lol: {}
 
@@ -2409,7 +2409,7 @@ def check_publication_info_from_empty(dirname):
 """
 
 
-def test_get_publication_info_from_complex_project(packages):
+def test_get_publication_info_from_complex_project(pkg_key):
     def check_publication_info_from_complex(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -2454,7 +2454,7 @@ def check_publication_info_from_complex(dirname):
             'env_specs': {
                 'default': {
                     'channels': ['bar'],
-                    f'{packages}': ['foo', 'notebook'],
+                    f'{pkg_key}': ['foo', 'notebook'],
                     'description': 'Default',
                     'locked': False,
                     'platforms': ['linux-64', 'osx-64', 'win-64'],
@@ -2490,7 +2490,7 @@ def check_publication_info_from_complex(dirname):
                 },
                 'lol': {
                     'channels': ['bar'],
-                    packages: ['foo'],
+                    pkg_key: ['foo'],
                     'description': 'lol',
                     'locked': False,
                     'platforms': ['linux-64', 'osx-64', 'win-64'],
@@ -2526,7 +2526,7 @@ def check_publication_info_from_complex(dirname):
                 },
                 'w00t': {
                     'channels': ['bar'],
-                    packages: ['foo', 'something'],
+                    pkg_key: ['foo', 'something'],
                     'description': 'double 0',
                     'locked': False,
                     'platforms': ['linux-64', 'osx-64', 'win-64'],
@@ -2562,7 +2562,7 @@ def check_publication_info_from_complex(dirname):
                 },
                 'woot': {
                     'channels': ['bar', 'woohoo'],
-                    packages: ['foo', 'blah', 'bokeh'],
+                    pkg_key: ['foo', 'blah', 'bokeh'],
                     'description': 'woot',
                     'locked': False,
                     'platforms': ['linux-64', 'osx-64', 'win-64'],
@@ -2604,13 +2604,13 @@ def check_publication_info_from_complex(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: _complicated_project_contents.replace('packages', packages),
+            DEFAULT_PROJECT_FILENAME: _complicated_project_contents.replace('<pkg_key>', pkg_key),
             "main.py": "",
             "foo.ipynb": ""
         }, check_publication_info_from_complex)
 
 
-def test_find_requirements(packages):
+def test_find_requirements(pkg_key):
     def check_find_requirements(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
@@ -2639,13 +2639,13 @@ def check_find_requirements(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: _complicated_project_contents.replace('packages', packages),
+            DEFAULT_PROJECT_FILENAME: _complicated_project_contents.replace('<pkg_key>', pkg_key),
             "main.py": "",
             "foo.ipynb": ""
         }, check_find_requirements)
 
 
-def test_requirements_subsets(packages):
+def test_requirements_subsets(pkg_key):
     def check_requirements_subsets(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
@@ -2671,13 +2671,13 @@ def check_requirements_subsets(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: _complicated_project_contents.replace('packages', packages),
+            DEFAULT_PROJECT_FILENAME: _complicated_project_contents.replace('<pkg_key>', pkg_key),
             "main.py": "",
             "foo.ipynb": ""
         }, check_requirements_subsets)
 
 
-def test_env_var_name_list_properties(packages):
+def test_env_var_name_list_properties(pkg_key):
     def check_env_var_name_list_properties(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
@@ -2697,7 +2697,7 @@ def check_env_var_name_list_properties(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: _complicated_project_contents.replace('packages', packages),
+            DEFAULT_PROJECT_FILENAME: _complicated_project_contents.replace('<pkg_key>', pkg_key),
             "main.py": "",
             "foo.ipynb": ""
         }, check_env_var_name_list_properties)
@@ -2806,7 +2806,7 @@ def check(dirname):
         }, check)
 
 
-def test_auto_fix_env_spec_out_of_sync(packages):
+def test_auto_fix_env_spec_out_of_sync(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert len(project.problems) == 1
@@ -2816,7 +2816,6 @@ def check(dirname):
         assert ("Environment spec 'stuff' from environment.yml is out of sync with anaconda-project.yml. Diff:\n" +
                 "  channels:\n    + bar\n+ a\n+ b\n  pip:\n    + foo") == problem.text
         assert problem.can_fix
-
         problem.fix(project)
         project.project_file.save()
 
@@ -2831,9 +2830,9 @@ def check(dirname):
         {
             DEFAULT_PROJECT_FILENAME: """
 name: foo
-env_specs: { 'stuff': { 'packages':[] } }
+env_specs: { 'stuff': { '<pkg_key>':[] } }
 platforms: [linux-32,linux-64,osx-64,win-32,win-64]
-""".lstrip().replace("packages", packages),
+""".lstrip().replace('<pkg_key>', pkg_key),
             "environment.yml":
             """
 name: stuff
@@ -2848,7 +2847,7 @@ def check(dirname):
         }, check)
 
 
-def test_auto_fix_env_spec_import_saying_no(packages):
+def test_auto_fix_env_spec_import_saying_no(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert len(project.problems) == 1
@@ -2872,9 +2871,9 @@ def check(dirname):
         {
             DEFAULT_PROJECT_FILENAME: """
 name: foo
-env_specs: {'default':{'packages':[]}}
+env_specs: {'default':{'<pkg_key>':[]}}
 platforms: [linux-32,linux-64,osx-64,win-32,win-64]
-""".lstrip().replace("packages", packages),
+""".lstrip().replace('<pkg_key>', pkg_key),
             "environment.yml": """
 name: stuff
 dependencies:
@@ -2889,7 +2888,7 @@ def check(dirname):
 
 
 @pytest._change_default_pkg_key
-def test_no_auto_fix_env_spec_with_notebook_bokeh_injection(packages):
+def test_no_auto_fix_env_spec_with_notebook_bokeh_injection(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert len(project.problems) == 1
@@ -2911,9 +2910,9 @@ def check(dirname):
         assert spec.channels == ('bar', )
 
         # add bokeh and notebook, which we should ignore
-        the_packages = project.project_file.get_value(['env_specs', 'stuff', packages])
+        the_packages = project.project_file.get_value(['env_specs', 'stuff', pkg_key])
         the_packages.extend(['bokeh', 'notebook'])
-        project.project_file.set_value(['env_specs', 'stuff', packages], the_packages)
+        project.project_file.set_value(['env_specs', 'stuff', pkg_key], the_packages)
         project.project_file.save()
 
         # no problems despite the diff
@@ -2922,17 +2921,17 @@ def check(dirname):
         assert spec.conda_packages == ('a', 'b', 'bokeh', 'notebook')
 
         # add some other package, should NOT ignore
-        the_packages = project.project_file.get_value(['env_specs', 'stuff', packages])
+        the_packages = project.project_file.get_value(['env_specs', 'stuff', pkg_key])
         the_packages.extend(['someother'])
-        project.project_file.set_value(['env_specs', 'stuff', packages], the_packages)
+        project.project_file.set_value(['env_specs', 'stuff', pkg_key], the_packages)
         project.project_file.save()
 
         assert len(project.problems) == 1
 
         # remove that again
-        the_packages = project.project_file.get_value(['env_specs', 'stuff', packages])
+        the_packages = project.project_file.get_value(['env_specs', 'stuff', pkg_key])
         the_packages.remove('someother')
-        project.project_file.set_value(['env_specs', 'stuff', packages], the_packages)
+        project.project_file.set_value(['env_specs', 'stuff', pkg_key], the_packages)
         project.project_file.save()
 
         assert len(project.problems) == 0
@@ -2956,7 +2955,7 @@ def check(dirname):
         assert len(project.problems) == 0
 
         # add a pip package, should NOT ignore
-        the_packages = project.project_file.get_value(['env_specs', 'stuff', packages])
+        the_packages = project.project_file.get_value(['env_specs', 'stuff', pkg_key])
         pip_list = None
         for p in the_packages:
             if isinstance(p, dict):
@@ -2973,9 +2972,9 @@ def check(dirname):
         {
             DEFAULT_PROJECT_FILENAME: """
 name: foo
-env_specs: { 'stuff': { 'packages':[] } }
+env_specs: { 'stuff': { '<pkg_key>':[] } }
 platforms: [linux-32,linux-64,osx-64,win-32,win-64]
-""".lstrip().replace("packages", packages),
+""".lstrip().replace('<pkg_key>', pkg_key),
             "environment.yml":
             """
 name: stuff
@@ -3022,7 +3021,7 @@ def check(dirname):
         }, check)
 
 
-def test_no_auto_fix_notebook_dep_if_we_have_anaconda(packages):
+def test_no_auto_fix_notebook_dep_if_we_have_anaconda(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3032,7 +3031,7 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: (f'{packages}:\n'
+            DEFAULT_PROJECT_FILENAME: (f'{pkg_key}:\n'
                                        ' - anaconda\n'
                                        'commands:\n'
                                        '  foo.ipynb:\n'
@@ -3042,7 +3041,7 @@ def check(dirname):
         }, check)
 
 
-def test_no_auto_fix_notebook_dep_if_we_have_notebook(packages):
+def test_no_auto_fix_notebook_dep_if_we_have_notebook(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3051,7 +3050,7 @@ def check(dirname):
 
     with_directory_contents_completing_project_file(
         {
-            DEFAULT_PROJECT_FILENAME: (f'{packages}:\n'
+            DEFAULT_PROJECT_FILENAME: (f'{pkg_key}:\n'
                                        ' - notebook\n'
                                        'commands:\n'
                                        '  foo.ipynb:\n'
@@ -3113,7 +3112,7 @@ def check(dirname):
         {DEFAULT_PROJECT_FILENAME: "commands:\n  foo:\n    unix: something\n    somejunk: True\n"}, check)
 
 
-def test_unknown_field_in_env_spec(packages):
+def test_unknown_field_in_env_spec(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
@@ -3121,10 +3120,10 @@ def check(dirname):
         assert [expected_suggestion] == project.suggestions
 
     with_directory_contents_completing_project_file(
-        {DEFAULT_PROJECT_FILENAME: f"env_specs:\n  foo:\n    {packages}: [something]\n    somejunk: True\n"}, check)
+        {DEFAULT_PROJECT_FILENAME: f"env_specs:\n  foo:\n    {pkg_key}: [something]\n    somejunk: True\n"}, check)
 
 
-def test_unknown_field_in_env_spec_allowed(packages):
+def test_unknown_field_in_env_spec_allowed(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
@@ -3133,7 +3132,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME:
-            f"env_specs:\n  foo:\n    {packages}: [something]\n    somejunk: True\n    user_fields: [somejunk]\n"
+            f"env_specs:\n  foo:\n    {pkg_key}: [something]\n    somejunk: True\n    user_fields: [somejunk]\n"
         }, check)
 
 
@@ -3174,7 +3173,7 @@ def check(dirname):
     with_directory_contents({DEFAULT_PROJECT_FILENAME: ""}, check)
 
 
-def test_with_one_locked_env_spec_has_problems(packages):
+def test_with_one_locked_env_spec_has_problems(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert [
@@ -3187,7 +3186,7 @@ def check(dirname):
             DEFAULT_PROJECT_FILENAME: f"""
 env_specs:
   foo:
-     {packages}: []
+     {pkg_key}: []
 """,
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"
         }, check)
@@ -3207,19 +3206,19 @@ def check(dirname):
     }, check)
 
 
-def test_with_locking_disabled_no_platforms_required(packages):
+def test_with_locking_disabled_no_platforms_required(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
 
     with_directory_contents(
         {
-            DEFAULT_PROJECT_FILENAME: f"name: foo\nenv_specs:\n  default:\n    {packages}: []\n",
+            DEFAULT_PROJECT_FILENAME: f"name: foo\nenv_specs:\n  default:\n    {pkg_key}: []\n",
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: false\n"
         }, check)
 
 
-def test_load_weird_platform(packages):
+def test_load_weird_platform(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3242,12 +3241,12 @@ def check(dirname):
 platforms: [linux-64, weird-valid, weirdinvalid]
 env_specs:
   default:
-    {packages}: [foo]
+    {pkg_key}: [foo]
 """
         }, check)
 
 
-def test_only_some_env_specs_have_platforms_locking_disabled(packages):
+def test_only_some_env_specs_have_platforms_locking_disabled(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
@@ -3260,14 +3259,14 @@ def check(dirname):
 env_specs:
   default:
     platforms: [linux-64]
-    {packages}: [foo]
+    {pkg_key}: [foo]
   no_platforms:
-    {packages}: [bar]
+    {pkg_key}: [bar]
 """
         }, check)
 
 
-def test_only_some_env_specs_have_platforms_locking_enabled(packages):
+def test_only_some_env_specs_have_platforms_locking_enabled(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert [("anaconda-project.yml: Env spec no_platforms does not have anything in its " + "'platforms:' field.")
@@ -3281,9 +3280,9 @@ def check(dirname):
 env_specs:
   default:
     platforms: [linux-64]
-    {packages}: [foo]
+    {pkg_key}: [foo]
   no_platforms:
-    {packages}: [bar]
+    {pkg_key}: [bar]
         """,
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"
         }, check)
@@ -3370,10 +3369,10 @@ def check(dirname):
 
 
 @pytest._change_default_pkg_key
-def test_lock_file_non_dict_lock_set_packages(packages):
+def test_lock_file_non_dict_lock_set_packages(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
-        expected_error = (f"%s: '{packages}:' section in env spec 'default' in lock file should be a dictionary, " +
+        expected_error = (f"%s: '{pkg_key}:' section in env spec 'default' in lock file should be a dictionary, " +
                           "found %r") % (project.lock_file.basename, 42)
         assert [expected_error] == project.problems
 
@@ -3381,12 +3380,12 @@ def check(dirname):
         {DEFAULT_PROJECT_LOCK_FILENAME: f"""
 env_specs:
   default:
-    {packages}: 42
+    {pkg_key}: 42
 """}, check)
 
 
 @pytest._change_default_pkg_key
-def test_lock_file_has_pip_packages(packages):
+def test_lock_file_has_pip_packages(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         assert [] == project.problems
@@ -3401,7 +3400,7 @@ def check(dirname):
 env_specs:
   default:
     platforms: [linux-64,osx-64,win-64]
-    {packages}:
+    {pkg_key}:
       all:
         - pip:
           - foobar
@@ -3410,7 +3409,7 @@ def check(dirname):
 
 
 @pytest._change_default_pkg_key
-def test_lock_file_has_invalid_packages(packages):
+def test_lock_file_has_invalid_packages(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3426,7 +3425,7 @@ def check(dirname):
             DEFAULT_PROJECT_LOCK_FILENAME: f"""
 env_specs:
   default:
-    {packages}:
+    {pkg_key}:
       all:
         - "="
         - foo bar
@@ -3436,7 +3435,7 @@ def check(dirname):
         }, check)
 
 
-def test_lock_file_has_wrong_platforms(packages):
+def test_lock_file_has_wrong_platforms(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3453,13 +3452,13 @@ def check(dirname):
 env_specs:
   default:
     platforms: ["win-64"]
-    {packages}:
+    {pkg_key}:
       all: [foo]
 """
         }, check)
 
 
-def test_lock_file_has_zero_platforms(packages):
+def test_lock_file_has_zero_platforms(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3474,12 +3473,12 @@ def check(dirname):
 env_specs:
   default:
     platforms: []
-    {packages}:
+    {pkg_key}:
       all: [foo]
 """}, check)
 
 
-def test_lock_file_has_wrong_hash(packages):
+def test_lock_file_has_wrong_hash(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3497,25 +3496,25 @@ def check(dirname):
   default:
     env_spec_hash: wrong
     platforms: [linux-64,osx-64,win-64]
-    {packages}:
+    {pkg_key}:
       all: [foo]
 """
         }, check)
 
 
 @pytest._change_default_pkg_key
-def test_lock_file_has_empty_and_wrong_package_lists(packages):
+def test_lock_file_has_empty_and_wrong_package_lists(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
         assert [] == project.problems
         # yapf: disable
         assert [
-            f'anaconda-project-lock.yml: Lock file lists no {packages} for env spec '
+            f'anaconda-project-lock.yml: Lock file lists no {pkg_key} for env spec '
             "'default' on platform linux-64",
-            f'anaconda-project-lock.yml: Lock file is missing 1 {packages} for env spec '
+            f'anaconda-project-lock.yml: Lock file is missing 1 {pkg_key} for env spec '
             'default on osx-64 (hello)',
-            f'anaconda-project-lock.yml: Lock file lists no {packages} for env spec '
+            f'anaconda-project-lock.yml: Lock file lists no {pkg_key} for env spec '
             "'default' on platform win-64"
         ] == project.suggestions
         # yapf: enable
@@ -3525,14 +3524,14 @@ def check(dirname):
             DEFAULT_PROJECT_FILENAME: f"""
 env_specs:
    default:
-      {packages}:
+      {pkg_key}:
          - hello
 """,
             DEFAULT_PROJECT_LOCK_FILENAME: f"""
 env_specs:
   default:
     platforms: [linux-64,osx-64,win-64]
-    {packages}:
+    {pkg_key}:
       linux-64: []
       win-64: []
       win-32: [foo]
@@ -3542,7 +3541,7 @@ def check(dirname):
         }, check)
 
 
-def test_lock_file_has_orphan_env_spec(packages):
+def test_lock_file_has_orphan_env_spec(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3555,23 +3554,23 @@ def check(dirname):
             DEFAULT_PROJECT_FILENAME: f"""
 env_specs:
    default:
-      {packages}:
+      {pkg_key}:
          - hello
 """,
             DEFAULT_PROJECT_LOCK_FILENAME: """
 env_specs:
   default:
     platforms: [linux-64,osx-64,win-64]
-    packages:
+    <pkg_key>:
       all: [hello]
   orphan:
     platforms: [linux-64,osx-64,win-64]
-    packages: {}
-""".replace('packages', packages)
+    <pkg_key>: {}
+""".replace('<pkg_key>', pkg_key)
         }, check)
 
 
-def test_fix_project_file_with_no_platforms(packages):
+def test_fix_project_file_with_no_platforms(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3592,7 +3591,7 @@ def check(dirname):
 name: foo
 env_specs:
    default:
-      {packages}:
+      {pkg_key}:
          - hello
 """,
             DEFAULT_PROJECT_LOCK_FILENAME: """
@@ -3601,7 +3600,7 @@ def check(dirname):
         }, check)
 
 
-def test_fix_env_spec_with_no_platforms(packages):
+def test_fix_env_spec_with_no_platforms(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -3629,15 +3628,15 @@ def check(dirname):
 env_specs:
    default:
       platforms: ['linux-64']
-      {packages}:
+      {pkg_key}:
          - hello
    foo:
       platforms: []
-      {packages}:
+      {pkg_key}:
          - apackage
    bar:
       platforms: []
-      {packages}:
+      {pkg_key}:
          - package2
 """,
             DEFAULT_PROJECT_LOCK_FILENAME: """
diff --git a/anaconda_project/test/test_project_ops.py b/anaconda_project/test/test_project_ops.py
index 47c695a5..c11ebc87 100644
--- a/anaconda_project/test/test_project_ops.py
+++ b/anaconda_project/test/test_project_ops.py
@@ -349,7 +349,7 @@ def check_add_var(dirname):
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: ""}, check_add_var)
 
 
-def test_add_variables_to_env_spec(packages):
+def test_add_variables_to_env_spec(pkg_key):
     def check_add_var(dirname):
         project = project_no_dedicated_env(dirname)
         status = project_ops.add_variables(project, 'myspec', ['foo', 'baz'], dict(foo='bar'))
@@ -366,10 +366,10 @@ def check_add_var(dirname):
             f"""
 env_specs:
     default:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
     myspec:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
 """
         }, check_add_var)
@@ -467,7 +467,7 @@ def check_remove_var(dirname):
                                     '  foo: baz\n  bar: qux')}, check_remove_var)
 
 
-def test_remove_variables_with_env_spec(packages):
+def test_remove_variables_with_env_spec(pkg_key):
     def check_remove_var(dirname):
         project = project_no_dedicated_env(dirname)
 
@@ -488,10 +488,10 @@ def check_remove_var(dirname):
             f"""
 env_specs:
   default:
-    {packages}: [python]
+    {pkg_key}: [python]
     channels: []
   myspec:
-    {packages}: [python]
+    {pkg_key}: [python]
     channels: []
     variables:
       foo: baz
@@ -716,7 +716,7 @@ def check_add_command(dirname):
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: ""}, check_add_command)
 
 
-def test_add_command_bokeh_overwrites(packages):
+def test_add_command_bokeh_overwrites(pkg_key):
     def check_add_command(dirname):
         project = project_no_dedicated_env(dirname)
         result = project_ops.add_command(project, 'bokeh_test', 'bokeh_app', 'file.py')
@@ -733,12 +733,12 @@ def check_add_command(dirname):
             DEFAULT_PROJECT_FILENAME: ('commands:\n'
                                        '  bokeh_test:\n'
                                        '    bokeh_app: replaced.py\n'
-                                       f'{packages}:\n'
+                                       f'{pkg_key}:\n'
                                        '  - bokeh\n')
         }, check_add_command)
 
 
-def test_add_command_sets_env_spec(packages):
+def test_add_command_sets_env_spec(pkg_key):
     def check_add_command(dirname):
         project = project_no_dedicated_env(dirname)
         result = project_ops.add_command(project, 'bokeh_test', 'bokeh_app', 'file.py', env_spec_name='foo')
@@ -752,14 +752,14 @@ def check_add_command(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: ('env_specs:\n'
-                                       f'  foo: {{ "{packages}" : ["bokeh"] }}\n'
+                                       f'  foo: {{ "{pkg_key}" : ["bokeh"] }}\n'
                                        'commands:\n'
                                        '  bokeh_test:\n'
                                        '    bokeh_app: replaced.py\n')
         }, check_add_command)
 
 
-def test_add_command_leaves_env_spec(packages):
+def test_add_command_leaves_env_spec(pkg_key):
     def check_add_command(dirname):
         project = project_no_dedicated_env(dirname)
         result = project_ops.add_command(project, 'bokeh_test', 'bokeh_app', 'file.py', env_spec_name=None)
@@ -773,7 +773,7 @@ def check_add_command(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: ('env_specs:\n'
-                                       f'  foo: {{ "{packages}" : ["bokeh"] }}\n'
+                                       f'  foo: {{ "{pkg_key}" : ["bokeh"] }}\n'
                                        'commands:\n'
                                        '  bokeh_test:\n'
                                        '    env_spec: "foo"\n'
@@ -782,7 +782,7 @@ def check_add_command(dirname):
 
 
 @pytest._change_default_pkg_key
-def test_add_command_generates_env_spec_suggestion(packages):
+def test_add_command_generates_env_spec_suggestion(pkg_key):
     def check_add_command(dirname):
         project = project_no_dedicated_env(dirname)
         assert project.problems == []
@@ -799,22 +799,22 @@ def check_add_command(dirname):
         command = re_loaded.get_value(['commands', 'bokeh_test'])
         assert command['bokeh_app'] == 'file.py'
         assert command['env_spec'] == 'bar'
-        assert re_loaded.get_value(['env_specs', 'bar', packages]) is None
+        assert re_loaded.get_value(['env_specs', 'bar', pkg_key]) is None
 
         assert project.problems == []
         assert project.suggestions == [('%s: Command ' % project.project_file.basename) +
-                                       f'bokeh_test uses env spec bar which does not have the {packages}: bokeh']
+                                       f'bokeh_test uses env spec bar which does not have the {pkg_key}: bokeh']
 
         project.fix_problems_and_suggestions()
         project.project_file.save()
 
         re_loaded = ProjectFile.load_for_directory(project.directory_path)
-        assert re_loaded.get_value(['env_specs', 'bar', packages]) == ['bokeh']
+        assert re_loaded.get_value(['env_specs', 'bar', pkg_key]) == ['bokeh']
 
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: ('env_specs:\n'
-                                       f'  foo: {{ "{packages}" : ["bokeh"] }}\n'
+                                       f'  foo: {{ "{pkg_key}" : ["bokeh"] }}\n'
                                        '  bar: {}\n'
                                        'commands:\n'
                                        '  bokeh_test:\n'
@@ -823,7 +823,7 @@ def check_add_command(dirname):
         }, check_add_command)
 
 
-def test_add_command_leaves_supports_http_options(packages):
+def test_add_command_leaves_supports_http_options(pkg_key):
     def check_add_command(dirname):
         project = project_no_dedicated_env(dirname)
         result = project_ops.add_command(project,
@@ -843,7 +843,7 @@ def check_add_command(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: ('env_specs:\n'
-                                       f'  foo: {{ "{packages}" : ["bokeh"] }}\n'
+                                       f'  foo: {{ "{pkg_key}" : ["bokeh"] }}\n'
                                        'commands:\n'
                                        '  bokeh_test:\n'
                                        '    supports_http_options: false\n'
@@ -851,7 +851,7 @@ def check_add_command(dirname):
         }, check_add_command)
 
 
-def test_add_command_leaves_supports_http_options_unset(packages):
+def test_add_command_leaves_supports_http_options_unset(pkg_key):
     def check_add_command(dirname):
         project = project_no_dedicated_env(dirname)
         result = project_ops.add_command(project,
@@ -871,14 +871,14 @@ def check_add_command(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: ('env_specs:\n'
-                                       f'  foo: {{ "{packages}" : ["bokeh"] }}\n'
+                                       f'  foo: {{ "{pkg_key}" : ["bokeh"] }}\n'
                                        'commands:\n'
                                        '  bokeh_test:\n'
                                        '    bokeh_app: replaced.py\n')
         }, check_add_command)
 
 
-def test_add_command_modifies_supports_http_options(packages):
+def test_add_command_modifies_supports_http_options(pkg_key):
     def check_add_command(dirname):
         project = project_no_dedicated_env(dirname)
         result = project_ops.add_command(project,
@@ -898,7 +898,7 @@ def check_add_command(dirname):
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: ('env_specs:\n'
-                                       f'  foo: {{ "{packages}" : ["bokeh"] }}\n'
+                                       f'  foo: {{ "{pkg_key}" : ["bokeh"] }}\n'
                                        'commands:\n'
                                        '  bokeh_test:\n'
                                        '    supports_http_options: false\n'
@@ -1253,7 +1253,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(dict(), check)
 
 
-def test_add_download_to_env_spec(monkeypatch, packages):
+def test_add_download_to_env_spec(monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_download_file(monkeypatch, dirname)
 
@@ -1276,10 +1276,10 @@ def check(dirname):
             r"""
 env_specs:
     default:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
     myspec:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
         """
         }, check)
@@ -1490,7 +1490,7 @@ def check(dirname):
 """}, check)
 
 
-def test_remove_download_with_env_spec(monkeypatch, packages):
+def test_remove_download_with_env_spec(monkeypatch, pkg_key):
     def check(dirname):
         config_path = ['env_specs', 'myspec', 'downloads', 'MYDATA']
         project = project_no_dedicated_env(dirname)
@@ -1510,10 +1510,10 @@ def check(dirname):
             f"""
 env_specs:
     default:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
     myspec:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
       downloads:
         MYDATA: "http://localhost:123456"
@@ -1529,7 +1529,7 @@ def check(dirname):
 # then we add a latest version of pandas. If anaconda-project does the right thing,
 # conda will install an earlier version of pandas to respect the numpy version pin.
 @pytest.mark.slow
-def test_add_env_spec_with_real_conda_manager(monkeypatch):
+def test_add_env_spec_with_real_conda_manager(monkeypatch, pkg_key):
     monkeypatch_conda_not_to_use_links(monkeypatch)
     _monkeypatch_reduced_environment(monkeypatch)
 
@@ -1539,9 +1539,9 @@ def check(dirname):
         pip_spec = ['chardet']
         for spec in specs:
             if spec == specs[0]:
-                status = project_ops.add_env_spec(project, name='foo', packages=[spec], channels=[])
+                status = project_ops.add_env_spec(project, name='foo', pkg_key=[spec], channels=[])
             else:
-                status = project_ops.add_packages(project, 'foo', packages=[spec], channels=[])
+                status = project_ops.add_packages(project, 'foo', pkg_key=[spec], channels=[])
             if not status:
                 print(status.status_description)
                 print(repr(status.errors))
@@ -1555,7 +1555,7 @@ def check(dirname):
             # be sure it was really done
             project2 = Project(dirname)
             env_commented_map = project2.project_file.get_value(['env_specs', 'foo'])
-            assert spec in env_commented_map['packages'], env_commented_map['packages']
+            assert spec in env_commented_map[pkg_key], env_commented_map[pkg_key]
 
             # ensure numpy <1.11.3 is present in both passes
             meta_path = os.path.join(dirname, 'envs', 'foo', 'conda-meta')
@@ -1635,7 +1635,8 @@ def _with_conda_test(f,
         _pop_conda_test()
 
 
-def test_add_env_spec():
+@pytest._change_default_pkg_key
+def test_add_env_spec(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1649,23 +1650,24 @@ def attempt():
 
         # be sure we really made the config changes
         project2 = Project(dirname)
-        assert dict(packages=[], channels=[]) == dict(project2.project_file.get_value(['env_specs', 'foo']))
-        assert dict(packages=[], channels=[]) == dict(project2.project_file.get_value(['env_specs', 'bar']))
-        assert dict(locked=True,
+        assert dict({pkg_key: []}, channels=[]) == dict(project2.project_file.get_value(['env_specs', 'foo']))
+        assert dict({pkg_key: []}, channels=[]) == dict(project2.project_file.get_value(['env_specs', 'bar']))
+        assert dict({pkg_key: dict(all=[])},
+                    locked=True,
                     env_spec_hash='a30f02c961ef4f3fe07ceb09e0906394c3885a79',
-                    packages=dict(all=[]),
                     platforms=['linux-64', 'osx-64',
                                'win-64']) == dict(project2.lock_file.get_value(['env_specs', 'foo']))
-        assert dict(locked=True,
+        assert dict({pkg_key: dict(all=[])},
+                    locked=True,
                     env_spec_hash='a30f02c961ef4f3fe07ceb09e0906394c3885a79',
-                    packages=dict(all=[]),
                     platforms=['linux-64', 'osx-64',
                                'win-64']) == dict(project2.lock_file.get_value(['env_specs', 'bar']))
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"}, check)
 
 
-def test_add_env_spec_no_global_platforms():
+@pytest._change_default_pkg_key
+def test_add_env_spec_no_global_platforms(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1686,20 +1688,21 @@ def attempt():
 
         # be sure we really made the config changes
         project2 = Project(dirname)
-        assert dict(packages=[], channels=[],
+        assert dict({pkg_key: []}, channels=[],
                     platforms=['linux-64', 'osx-64',
                                'win-64']) == dict(project2.project_file.get_value(['env_specs', 'foo']))
 
-        assert dict(locked=True,
+        assert dict({pkg_key: dict(all=[])},
+                    locked=True,
                     env_spec_hash='a30f02c961ef4f3fe07ceb09e0906394c3885a79',
-                    packages=dict(all=[]),
                     platforms=['linux-64', 'osx-64',
                                'win-64']) == dict(project2.lock_file.get_value(['env_specs', 'foo']))
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"}, check)
 
 
-def test_add_env_spec_with_packages_and_channels():
+@pytest._change_default_pkg_key
+def test_add_env_spec_with_packages_and_channels(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1713,7 +1716,7 @@ def attempt():
 
         # be sure download was added to the file and saved
         project2 = Project(dirname)
-        assert dict(packages=['a', 'b', 'c'],
+        assert dict({pkg_key: ['a', 'b', 'c']},
                     channels=['c1', 'c2', 'c3']) == dict(project2.project_file.get_value(['env_specs', 'foo']))
 
         env_spec = project2.env_specs['foo']
@@ -1725,7 +1728,7 @@ def attempt():
 
 
 @pytest._change_default_pkg_key
-def test_add_env_spec_extending_existing_lists(packages):
+def test_add_env_spec_extending_existing_lists(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1739,20 +1742,20 @@ def attempt():
 
         # be sure download was added to the file and saved
         project2 = Project(dirname)
-        assert dict({packages: ['b', 'a', 'c']},
+        assert dict({pkg_key: ['b', 'a', 'c']},
                     channels=['c3', 'c1', 'c2']) == dict(project2.project_file.get_value(['env_specs', 'foo']))
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: f"""
 env_specs:
   foo:
-    {packages}: [ 'b' ]
+    {pkg_key}: [ 'b' ]
     channels: [ 'c3']
 """}, check)
 
 
 @pytest._change_default_pkg_key
-def test_add_env_spec_extending_existing_lists_with_versions(packages):
+def test_add_env_spec_extending_existing_lists_with_versions(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1766,14 +1769,14 @@ def attempt():
 
         # be sure download was added to the file and saved
         project2 = Project(dirname)
-        assert dict({packages: ['b=2.0', 'a', 'c']},
+        assert dict({pkg_key: ['b=2.0', 'a', 'c']},
                     channels=['c3', 'c1', 'c2']) == dict(project2.project_file.get_value(['env_specs', 'foo']))
 
     with_directory_contents_completing_project_file(
         {DEFAULT_PROJECT_FILENAME: f"""
 env_specs:
   foo:
-    {packages}: [ 'b=1.0' ]
+    {pkg_key}: [ 'b=1.0' ]
     channels: [ 'c3']
 """}, check)
 
@@ -1799,7 +1802,7 @@ def attempt():
 
 
 @pytest._change_default_pkg_key
-def test_remove_env_spec(packages):
+def test_remove_env_spec(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1828,10 +1831,10 @@ def attempt():
 name: foo
 env_specs:
   hello:
-   {packages}:
+   {pkg_key}:
      - a
   another:
-   {packages}:
+   {pkg_key}:
      - b
     """,
             DEFAULT_PROJECT_LOCK_FILENAME: f"""
@@ -1839,14 +1842,14 @@ def attempt():
 env_specs:
   hello:
     platforms: [linux-32,linux-64,osx-64,win-32,win-64]
-    {packages}:
+    {pkg_key}:
       all:
       - a=1.0=1
 """
         }, check)
 
 
-def test_remove_only_env_spec(packages):
+def test_remove_only_env_spec(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1871,13 +1874,13 @@ def attempt():
 name: foo
 env_specs:
   hello:
-   {packages}:
+   {pkg_key}:
      - a
     """}, check)
 
 
 @pytest._change_default_pkg_key
-def test_remove_env_spec_causes_problem(packages):
+def test_remove_env_spec_causes_problem(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1912,10 +1915,10 @@ def attempt():
     env_spec: hello
 env_specs:
   hello:
-   {packages}:
+   {pkg_key}:
      - a
   another:
-   {packages}:
+   {pkg_key}:
      - b
     """,
             DEFAULT_PROJECT_LOCK_FILENAME: f"""
@@ -1923,14 +1926,14 @@ def attempt():
 env_specs:
   hello:
     platforms: [linux-32,linux-64,osx-64,win-32,win-64]
-    {packages}:
+    {pkg_key}:
       all:
       - a=1.0=1
 """
         }, check)
 
 
-def test_add_packages_to_all_environments(packages):
+def test_add_packages_to_all_environments(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1945,7 +1948,7 @@ def attempt():
 
         # be sure we really made the config changes
         project2 = Project(dirname)
-        assert [dict(pip=[]), 'foo', 'bar'] == list(project2.project_file.get_value(packages))
+        assert [dict(pip=[]), 'foo', 'bar'] == list(project2.project_file.get_value(pkg_key))
         assert ['hello', 'world'] == list(project2.project_file.get_value('channels'))
 
         for env_spec in project2.env_specs.values():
@@ -1956,14 +1959,14 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
  - pip: [] # be sure we don't break with this in the list
                 """,
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"
         }, check)
 
 
-def test_add_pip_packages_to_all_environments(packages):
+def test_add_pip_packages_to_all_environments(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -1981,7 +1984,7 @@ def attempt():
         project2 = Project(dirname)
         assert [
             dict(pip=['foo', 'bar']),
-        ] == list(project2.project_file.get_value(packages))
+        ] == list(project2.project_file.get_value(pkg_key))
         # assert ['hello', 'world'] == list(project2.project_file.get_value('channels'))
 
         for env_spec in project2.env_specs.values():
@@ -1992,14 +1995,14 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
  - pip: [] # be sure we don't break with this in the list
                 """,
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"
         }, check)
 
 
-def test_add_packages_cannot_resolve_deps():
+def test_add_packages_cannot_resolve_deps(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname, frontend=FakeFrontend())
@@ -2016,7 +2019,7 @@ def attempt():
 
         # be sure we didn't make the config changes
         project2 = Project(dirname)
-        assert project2.project_file.get_value('packages', None) is None
+        assert project2.project_file.get_value(pkg_key, None) is None
         assert project2.project_file.get_value('channels', None) is None
 
         for env_spec in project2.env_specs.values():
@@ -2056,7 +2059,7 @@ def attempt():
     with_directory_contents_completing_project_file(dict(), check)
 
 
-def test_remove_packages_from_all_environments(packages):
+def test_remove_packages_from_all_environments(pkg_key):
     def check(dirname):
         def attempt():
             os.makedirs(os.path.join(dirname, 'envs', 'hello'))  # forces us to really run remove_packages
@@ -2065,8 +2068,8 @@ def attempt():
                 assert env_spec.lock_set.enabled
                 assert env_spec.lock_set.platforms == ()
 
-            assert ['foo', 'bar', 'baz'] == list(project.project_file.get_value(packages))
-            assert ['foo', 'woot'] == list(project.project_file.get_value(['env_specs', 'hello', packages], []))
+            assert ['foo', 'bar', 'baz'] == list(project.project_file.get_value(pkg_key))
+            assert ['foo', 'woot'] == list(project.project_file.get_value(['env_specs', 'hello', pkg_key], []))
             status = project_ops.remove_packages(project, env_spec_name=None, packages=['foo', 'bar'])
             assert [] == status.errors
             assert status
@@ -2075,8 +2078,8 @@ def attempt():
 
         # be sure we really made the config changes
         project2 = Project(dirname)
-        assert ['baz'] == list(project2.project_file.get_value(packages))
-        assert ['woot'] == list(project2.project_file.get_value(['env_specs', 'hello', packages]))
+        assert ['baz'] == list(project2.project_file.get_value(pkg_key))
+        assert ['woot'] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key]))
 
         for env_spec in project2.env_specs.values():
             assert env_spec.lock_set.enabled
@@ -2086,17 +2089,17 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   - foo
   - bar
   - baz
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
      - foo
      - woot
   hello2:
-    {packages}:
+    {pkg_key}:
      - foo
      - bar
      - pip: [] # make sure we don't choke on non-string items in list
@@ -2105,7 +2108,7 @@ def attempt():
         }, check)
 
 
-def test_remove_conda_packages_from_global_with_pip_packages(packages):
+def test_remove_conda_packages_from_global_with_pip_packages(pkg_key):
     def check(dirname):
         def attempt():
             os.makedirs(os.path.join(dirname, 'envs', 'hello'))  # forces us to really run remove_packages
@@ -2114,8 +2117,8 @@ def attempt():
                 assert env_spec.lock_set.enabled
                 assert env_spec.lock_set.platforms == ()
 
-            assert ['foo', 'bar', 'baz', OrderedDict([('pip', [])])] == list(project.project_file.get_value(packages))
-            assert ['foo', 'woot'] == list(project.project_file.get_value(['env_specs', 'hello', packages], []))
+            assert ['foo', 'bar', 'baz', OrderedDict([('pip', [])])] == list(project.project_file.get_value(pkg_key))
+            assert ['foo', 'woot'] == list(project.project_file.get_value(['env_specs', 'hello', pkg_key], []))
             status = project_ops.remove_packages(project, env_spec_name=None, packages=['foo', 'bar'])
             assert [] == status.errors
             assert status
@@ -2124,8 +2127,8 @@ def attempt():
 
         # be sure we really made the config changes
         project2 = Project(dirname)
-        assert ['baz', OrderedDict([('pip', [])])] == list(project2.project_file.get_value(packages))
-        assert ['woot'] == list(project2.project_file.get_value(['env_specs', 'hello', packages]))
+        assert ['baz', OrderedDict([('pip', [])])] == list(project2.project_file.get_value(pkg_key))
+        assert ['woot'] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key]))
 
         for env_spec in project2.env_specs.values():
             assert env_spec.lock_set.enabled
@@ -2135,18 +2138,18 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   - foo
   - bar
   - baz
   - pip: []
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
      - foo
      - woot
   hello2:
-    {packages}:
+    {pkg_key}:
      - foo
      - bar
      - pip: [] # make sure we don't choke on non-string items in list
@@ -2155,7 +2158,7 @@ def attempt():
         }, check)
 
 
-def test_remove_pip_packages_from_global(packages):
+def test_remove_pip_packages_from_global(pkg_key):
     def check(dirname):
         def attempt():
             os.makedirs(os.path.join(dirname, 'envs', 'hello'))  # forces us to really run remove_packages
@@ -2164,9 +2167,9 @@ def attempt():
                 assert env_spec.lock_set.enabled
                 assert env_spec.lock_set.platforms == ()
 
-            assert ['foo', OrderedDict([('pip', ['bar', 'baz'])])] == list(project.project_file.get_value(packages))
+            assert ['foo', OrderedDict([('pip', ['bar', 'baz'])])] == list(project.project_file.get_value(pkg_key))
             assert ['foo', OrderedDict([('pip', ['bar', 'woot'])])
-                    ] == list(project.project_file.get_value(['env_specs', 'hello', packages], []))
+                    ] == list(project.project_file.get_value(['env_specs', 'hello', pkg_key], []))
             status = project_ops.remove_packages(project, env_spec_name=None, packages=['bar'], pip=True)
             assert [] == status.errors
             assert status
@@ -2175,9 +2178,9 @@ def attempt():
 
         # be sure we really made the config changes
         project2 = Project(dirname)
-        assert ['foo', OrderedDict([('pip', ['baz'])])] == list(project2.project_file.get_value(packages))
+        assert ['foo', OrderedDict([('pip', ['baz'])])] == list(project2.project_file.get_value(pkg_key))
         assert ['foo', OrderedDict([('pip', ['woot'])])
-                ] == list(project2.project_file.get_value(['env_specs', 'hello', packages]))
+                ] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key]))
 
         for env_spec in project2.env_specs.values():
             assert env_spec.lock_set.enabled
@@ -2187,14 +2190,14 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   - foo
   - pip:
     - bar
     - baz
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
      - foo
      - pip:
        - bar
@@ -2205,7 +2208,7 @@ def attempt():
         }, check)
 
 
-def test_remove_pip_packages_from_one_environment(packages):
+def test_remove_pip_packages_from_one_environment(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -2215,7 +2218,7 @@ def attempt():
                 assert env_spec.lock_set.platforms == ()
 
             assert ['qbert', OrderedDict([('pip', ['pbert', 'foo',
-                                                   'bar'])])] == list(project.project_file.get_value(packages))
+                                                   'bar'])])] == list(project.project_file.get_value(pkg_key))
             status = project_ops.remove_packages(project, env_spec_name='hello', packages=['foo', 'bar'], pip=True)
             assert status
             assert [] == status.errors
@@ -2226,9 +2229,9 @@ def attempt():
         project2 = Project(dirname)
         # note that hello will still inherit the deps from the global packages,
         # and that's fine
-        assert ['qbert', OrderedDict([('pip', ['pbert'])])] == list(project2.project_file.get_value(packages))
+        assert ['qbert', OrderedDict([('pip', ['pbert'])])] == list(project2.project_file.get_value(pkg_key))
         assert [OrderedDict([('pip', [])])
-                ] == list(project2.project_file.get_value(['env_specs', 'hello', packages], []))
+                ] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key], []))
 
         # be sure we didn't delete comments from global packages section
         content = codecs.open(project2.project_file.filename, 'r', 'utf-8').read()
@@ -2246,7 +2249,7 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   # this is a pre comment
   - qbert # this is a post comment
   - pip:
@@ -2255,7 +2258,7 @@ def attempt():
     - bar
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
       - pip:
         - foo
         """,
@@ -2263,7 +2266,7 @@ def attempt():
         }, check)
 
 
-def test_remove_pip_packages_from_one_environment_with_pkgs(packages):
+def test_remove_pip_packages_from_one_environment_with_pkgs(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -2273,7 +2276,7 @@ def attempt():
                 assert env_spec.lock_set.platforms == ()
 
             assert ['qbert', OrderedDict([('pip', ['pbert', 'foo',
-                                                   'bar'])])] == list(project.project_file.get_value(packages))
+                                                   'bar'])])] == list(project.project_file.get_value(pkg_key))
             status = project_ops.remove_packages(project, env_spec_name='hello', packages=['foo', 'bar'], pip=True)
             assert status
             assert [] == status.errors
@@ -2284,9 +2287,9 @@ def attempt():
         project2 = Project(dirname)
         # note that hello will still inherit the deps from the global packages,
         # and that's fine
-        assert ['qbert', OrderedDict([('pip', ['pbert'])])] == list(project2.project_file.get_value(packages))
+        assert ['qbert', OrderedDict([('pip', ['pbert'])])] == list(project2.project_file.get_value(pkg_key))
         assert ['qbert', OrderedDict([('pip', [])])
-                ] == list(project2.project_file.get_value(['env_specs', 'hello', packages], []))
+                ] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key], []))
 
         # be sure we didn't delete comments from global packages section
         content = codecs.open(project2.project_file.filename, 'r', 'utf-8').read()
@@ -2304,7 +2307,7 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   # this is a pre comment
   - qbert # this is a post comment
   - pip:
@@ -2313,14 +2316,14 @@ def attempt():
     - bar
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
       - qbert
         """,
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"
         }, check)
 
 
-def test_remove_pip_packages_from_one_environment_empty_pkgs(packages):
+def test_remove_pip_packages_from_one_environment_empty_pkgs(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -2330,7 +2333,7 @@ def attempt():
                 assert env_spec.lock_set.platforms == ()
 
             assert ['qbert', OrderedDict([('pip', ['pbert', 'foo',
-                                                   'bar'])])] == list(project.project_file.get_value(packages))
+                                                   'bar'])])] == list(project.project_file.get_value(pkg_key))
             status = project_ops.remove_packages(project, env_spec_name='hello', packages=['foo', 'bar'], pip=True)
             assert status
             assert [] == status.errors
@@ -2341,9 +2344,9 @@ def attempt():
         project2 = Project(dirname)
         # note that hello will still inherit the deps from the global packages,
         # and that's fine
-        assert ['qbert', OrderedDict([('pip', ['pbert'])])] == list(project2.project_file.get_value(packages))
+        assert ['qbert', OrderedDict([('pip', ['pbert'])])] == list(project2.project_file.get_value(pkg_key))
         assert [OrderedDict([('pip', [])])
-                ] == list(project2.project_file.get_value(['env_specs', 'hello', packages], []))
+                ] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key], []))
 
         # be sure we didn't delete comments from global packages section
         content = codecs.open(project2.project_file.filename, 'r', 'utf-8').read()
@@ -2361,7 +2364,7 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   # this is a pre comment
   - qbert # this is a post comment
   - pip:
@@ -2370,13 +2373,13 @@ def attempt():
     - bar
 env_specs:
   hello:
-    {packages}: []
+    {pkg_key}: []
         """,
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"
         }, check)
 
 
-def test_remove_packages_from_one_environment(packages):
+def test_remove_packages_from_one_environment(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
@@ -2385,8 +2388,8 @@ def attempt():
                 assert env_spec.lock_set.enabled
                 assert env_spec.lock_set.platforms == ()
 
-            assert ['qbert', 'foo', 'bar'] == list(project.project_file.get_value(packages))
-            assert ['foo'] == list(project.project_file.get_value(['env_specs', 'hello', packages], []))
+            assert ['qbert', 'foo', 'bar'] == list(project.project_file.get_value(pkg_key))
+            assert ['foo'] == list(project.project_file.get_value(['env_specs', 'hello', pkg_key], []))
             status = project_ops.remove_packages(project, env_spec_name='hello', packages=['foo', 'bar'])
             assert status
             assert [] == status.errors
@@ -2397,8 +2400,8 @@ def attempt():
         project2 = Project(dirname)
         # note that hello will still inherit the deps from the global packages,
         # and that's fine
-        assert ['qbert'] == list(project2.project_file.get_value(packages))
-        assert [] == list(project2.project_file.get_value(['env_specs', 'hello', packages], []))
+        assert ['qbert'] == list(project2.project_file.get_value(pkg_key))
+        assert [] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key], []))
 
         # be sure we didn't delete comments from global packages section
         content = codecs.open(project2.project_file.filename, 'r', 'utf-8').read()
@@ -2416,26 +2419,26 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   # this is a pre comment
   - qbert # this is a post comment
   - foo
   - bar
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
      - foo
         """,
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"
         }, check)
 
 
-def test_remove_packages_from_one_environment_leaving_others_unaffected(packages):
+def test_remove_packages_from_one_environment_leaving_others_unaffected(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
-            assert ['qbert', 'foo', 'bar'] == list(project.project_file.get_value(packages))
-            assert ['foo'] == list(project.project_file.get_value(['env_specs', 'hello', packages], []))
+            assert ['qbert', 'foo', 'bar'] == list(project.project_file.get_value(pkg_key))
+            assert ['foo'] == list(project.project_file.get_value(['env_specs', 'hello', pkg_key], []))
             status = project_ops.remove_packages(project, env_spec_name='hello', packages=['foo', 'bar'])
             assert status
             assert [] == status.errors
@@ -2444,10 +2447,10 @@ def attempt():
 
         # be sure we really made the config changes
         project2 = Project(dirname)
-        assert ['qbert'] == list(project2.project_file.get_value(packages))
-        assert [] == list(project2.project_file.get_value(['env_specs', 'hello', packages], []))
+        assert ['qbert'] == list(project2.project_file.get_value(pkg_key))
+        assert [] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key], []))
         assert set(['baz', 'foo',
-                    'bar']) == set(project2.project_file.get_value(['env_specs', 'another', packages], []))
+                    'bar']) == set(project2.project_file.get_value(['env_specs', 'another', pkg_key], []))
         assert project2.env_specs['another'].conda_package_names_set == set(['qbert', 'foo', 'bar', 'baz'])
         assert project2.env_specs['hello'].conda_package_names_set == set(['qbert'])
 
@@ -2459,28 +2462,28 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   - qbert
   - foo
   - bar
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
      - foo
   another:
-    {packages}:
+    {pkg_key}:
      # this is a pre comment
      - baz # this is a post comment
 """
         }, check)
 
 
-def test_remove_pip_packages_from_one_environment_leaving_others_unaffected(packages):
+def test_remove_pip_packages_from_one_environment_leaving_others_unaffected(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
             assert ['qbert', OrderedDict([('pip', ['pbert', 'foo',
-                                                   'bar'])])] == list(project.project_file.get_value(packages))
+                                                   'bar'])])] == list(project.project_file.get_value(pkg_key))
             status = project_ops.remove_packages(project, env_spec_name='hello', packages=['foo', 'bar'], pip=True)
             assert status
             assert [] == status.errors
@@ -2489,11 +2492,11 @@ def attempt():
 
         # be sure we really made the config changes
         project2 = Project(dirname)
-        assert ['qbert', OrderedDict([('pip', ['pbert'])])] == list(project2.project_file.get_value(packages))
+        assert ['qbert', OrderedDict([('pip', ['pbert'])])] == list(project2.project_file.get_value(pkg_key))
         assert [OrderedDict([('pip', [])])
-                ] == list(project2.project_file.get_value(['env_specs', 'hello', packages], []))
+                ] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key], []))
         assert set(['baz', 'foo',
-                    'bar']) == set(project2.project_file.get_value(['env_specs', 'another', packages], [])[0]['pip'])
+                    'bar']) == set(project2.project_file.get_value(['env_specs', 'another', pkg_key], [])[0]['pip'])
         assert project2.env_specs['another'].pip_package_names_set == set(['foo', 'bar', 'baz', 'pbert'])
         assert project2.env_specs['hello'].pip_package_names_set == set(['pbert'])
 
@@ -2505,7 +2508,7 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   - qbert
   - pip:
     - pbert
@@ -2513,11 +2516,11 @@ def attempt():
     - bar
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
      - pip:
        - foo
   another:
-    {packages}:
+    {pkg_key}:
       - pip:
         # this is a pre comment
         - baz # this is a post comment
@@ -2525,7 +2528,7 @@ def attempt():
         }, check)
 
 
-def test_remove_packages_cannot_resolve_deps(packages):
+def test_remove_packages_cannot_resolve_deps(pkg_key):
     def check(dirname):
         def attempt():
             os.makedirs(os.path.join(dirname, 'envs', 'hello'))  # forces us to really run remove_packages
@@ -2534,8 +2537,8 @@ def attempt():
                 assert env_spec.lock_set.enabled
                 assert env_spec.lock_set.platforms == ()
 
-            assert ['foo', 'bar', 'baz'] == list(project.project_file.get_value(packages))
-            assert ['foo', 'woot'] == list(project.project_file.get_value(['env_specs', 'hello', packages], []))
+            assert ['foo', 'bar', 'baz'] == list(project.project_file.get_value(pkg_key))
+            assert ['foo', 'woot'] == list(project.project_file.get_value(['env_specs', 'hello', pkg_key], []))
             status = project_ops.remove_packages(project, env_spec_name=None, packages=['foo', 'bar'])
             assert status.status_description == "Error resolving dependencies for hello: NOPE."
             assert status.errors == []
@@ -2546,8 +2549,8 @@ def attempt():
 
         # be sure we didn't make the config changes
         project2 = Project(dirname)
-        assert ['foo', 'bar', 'baz'] == list(project2.project_file.get_value(packages))
-        assert ['foo', 'woot'] == list(project2.project_file.get_value(['env_specs', 'hello', packages]))
+        assert ['foo', 'bar', 'baz'] == list(project2.project_file.get_value(pkg_key))
+        assert ['foo', 'woot'] == list(project2.project_file.get_value(['env_specs', 'hello', pkg_key]))
 
         for env_spec in project2.env_specs.values():
             assert env_spec.lock_set.enabled
@@ -2556,13 +2559,13 @@ def attempt():
     with_directory_contents_completing_project_file(
         {
             DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   - foo
   - bar
   - baz
 env_specs:
   hello:
-    {packages}:
+    {pkg_key}:
      - foo
      - woot
         """,
@@ -2570,11 +2573,11 @@ def attempt():
         }, check)
 
 
-def test_remove_packages_from_nonexistent_environment(packages):
+def test_remove_packages_from_nonexistent_environment(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname)
-            assert ['foo', 'bar'] == list(project.project_file.get_value(packages))
+            assert ['foo', 'bar'] == list(project.project_file.get_value(pkg_key))
             status = project_ops.remove_packages(project, env_spec_name='not_an_environment', packages=['foo', 'bar'])
             assert not status
             assert [] == status.errors
@@ -2584,10 +2587,10 @@ def attempt():
 
         # be sure we didn't make the config changes
         project2 = Project(dirname)
-        assert ['foo', 'bar'] == list(project2.project_file.get_value(packages))
+        assert ['foo', 'bar'] == list(project2.project_file.get_value(pkg_key))
 
     with_directory_contents_completing_project_file({DEFAULT_PROJECT_FILENAME: f"""
-{packages}:
+{pkg_key}:
   - foo
   - bar
 """}, check)
@@ -2924,7 +2927,7 @@ def attempt():
 
 
 @pytest._change_default_pkg_key
-def test_lock_and_update_and_unlock_all_envs(packages):
+def test_lock_and_update_and_unlock_all_envs(pkg_key):
     def check(dirname):
         resolve_results = {'all': ['a=1.0=1'], 'pip': ['cc==1.0']}
 
@@ -2950,7 +2953,7 @@ def attempt():
                 '+   linux-64',
                 '+   osx-64',
                 '+   win-64',
-                f'  {packages}:',
+                f'  {pkg_key}:',
                 '+   all:',
                 '+     a=1.0=1',
                 '+   pip:',
@@ -2962,7 +2965,7 @@ def attempt():
                 '+   linux-64',
                 '+   osx-64',
                 '+   win-64',
-                f'  {packages}:',
+                f'  {pkg_key}:',
                 '+   all:',
                 '+     a=1.0=1',
                 '+   pip:',
@@ -3049,12 +3052,12 @@ def attempt():
 name: locktest
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
       - pip:
         - cc
   bar:
-    {packages}:
+    {pkg_key}:
       - b
       - pip:
         - dd
@@ -3063,7 +3066,7 @@ def attempt():
 
 
 @pytest._change_default_pkg_key
-def test_lock_and_unlock_single_env(packages):
+def test_lock_and_unlock_single_env(pkg_key):
     def check(dirname):
         def attempt():
             filename = os.path.join(dirname, DEFAULT_PROJECT_LOCK_FILENAME)
@@ -3087,7 +3090,7 @@ def attempt():
                     '+   linux-64',
                     '+   osx-64',
                     '+   win-64',
-                    f'  {packages}:',
+                    f'  {pkg_key}:',
                     '+   all:',
                     '+     a=1.0=1',
                     'Added locked dependencies for env spec foo to anaconda-project-lock.yml.'] == project.frontend.logs
@@ -3169,18 +3172,18 @@ def attempt():
 name: locktest
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
   bar:
     platforms: [osx-64]
-    {packages}:
+    {pkg_key}:
       - b
 """
         }, check)
 
 
 @pytest._change_default_pkg_key
-def test_locking_with_missing_lock_set_does_an_update(packages):
+def test_locking_with_missing_lock_set_does_an_update(pkg_key):
     def check(dirname):
         def attempt():
             filename = os.path.join(dirname, DEFAULT_PROJECT_LOCK_FILENAME)
@@ -3205,7 +3208,7 @@ def attempt():
                     '+   linux-64',
                     '+   osx-64',
                     '+   win-64',
-                    f'  {packages}:',
+                    f'  {pkg_key}:',
                     '+   all:',
                     '+     a=1.0=1',
                     'Added locked dependencies for env spec foo to anaconda-project-lock.yml.'] == project.frontend.logs
@@ -3231,7 +3234,7 @@ def attempt():
 platforms: [linux-64,osx-64,win-64]
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
         """,
             DEFAULT_PROJECT_LOCK_FILENAME: """
@@ -3242,7 +3245,7 @@ def attempt():
 
 
 @pytest._change_default_pkg_key
-def test_update_changes_only_the_hash(packages):
+def test_update_changes_only_the_hash(pkg_key):
     def check(dirname):
         def attempt():
             project = Project(dirname, frontend=FakeFrontend())
@@ -3277,7 +3280,7 @@ def attempt():
 platforms: [linux-32,linux-64,osx-64,win-32,win-64]
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
 """,
             DEFAULT_PROJECT_LOCK_FILENAME: f"""
@@ -3286,13 +3289,13 @@ def attempt():
   foo:
     platforms: [linux-32,linux-64,osx-64,win-32,win-64]
     env_spec_hash: old
-    {packages}:
+    {pkg_key}:
       all: ['a=1.0=1']
 """
         }, check)
 
 
-def test_lock_conda_error(packages):
+def test_lock_conda_error(pkg_key):
     def check(dirname):
         def attempt():
             filename = os.path.join(dirname, DEFAULT_PROJECT_LOCK_FILENAME)
@@ -3318,16 +3321,16 @@ def attempt():
 platforms: [linux-32,linux-64,osx-64,win-32,win-64]
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
   bar:
-    {packages}:
+    {pkg_key}:
       - b
 """
         }, check)
 
 
-def test_lock_resolve_dependencies_error(monkeypatch, packages):
+def test_lock_resolve_dependencies_error(monkeypatch, pkg_key):
     def check(dirname):
         def attempt():
             filename = os.path.join(dirname, DEFAULT_PROJECT_LOCK_FILENAME)
@@ -3350,16 +3353,16 @@ def attempt():
 platforms: [linux-32,linux-64,osx-64,win-32,win-64]
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
   bar:
-    {packages}:
+    {pkg_key}:
       - b
 """
         }, check)
 
 
-def test_unlock_conda_error(packages):
+def test_unlock_conda_error(pkg_key):
     def check(dirname):
         def attempt():
             filename = os.path.join(dirname, DEFAULT_PROJECT_LOCK_FILENAME)
@@ -3392,10 +3395,10 @@ def attempt():
 platforms: [linux-32,linux-64,osx-64,win-32,win-64]
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
   bar:
-    {packages}:
+    {pkg_key}:
       - b
 """,
             DEFAULT_PROJECT_LOCK_FILENAME: f"""
@@ -3404,20 +3407,20 @@ def attempt():
   foo:
     locked: true
     platforms: [linux-32,linux-64,osx-64,win-32,win-64]
-    {packages}:
+    {pkg_key}:
        all:
          - c
   bar:
     locked: true
     platforms: [linux-32,linux-64,osx-64,win-32,win-64]
-    {packages}:
+    {pkg_key}:
        all:
          - d
 """
         }, check)
 
 
-def test_update_unlocked_envs(packages):
+def test_update_unlocked_envs(pkg_key):
     def check(dirname):
         resolve_results = {'all': ['a=1.0=1']}
 
@@ -3457,17 +3460,17 @@ def attempt():
 platforms: [linux-32,linux-64,osx-64,win-32,win-64]
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
   bar:
-    {packages}:
+    {pkg_key}:
       - b
 """
         }, check)
 
 
 @pytest._change_default_pkg_key
-def test_update_empty_lock_sets(packages):
+def test_update_empty_lock_sets(pkg_key):
     def check(dirname):
         resolve_results = {'all': ['a=1.0=1']}
 
@@ -3493,7 +3496,7 @@ def attempt():
                 '+   linux-64',
                 '+   osx-64',
                 '+   win-64',
-                f'  {packages}:',
+                f'  {pkg_key}:',
                 '+   all:',
                 '+     a=1.0=1',
                 'Updated locked dependencies for env spec bar in anaconda-project-lock.yml.',
@@ -3503,7 +3506,7 @@ def attempt():
                 '+   linux-64',
                 '+   osx-64',
                 '+   win-64',
-                f'  {packages}:',
+                f'  {pkg_key}:',
                 '+   all:',
                 '+     a=1.0=1',
                 'Updated locked dependencies for env spec foo in anaconda-project-lock.yml.'
@@ -3524,17 +3527,17 @@ def attempt():
 platforms: [linux-64,osx-64,win-64]
 env_specs:
   foo:
-    {packages}:
+    {pkg_key}:
       - a
   bar:
-    {packages}:
+    {pkg_key}:
       - b
         """,
             DEFAULT_PROJECT_LOCK_FILENAME: "locking_enabled: true\n"
         }, check)
 
 
-def test_export_env_spec(packages):
+def test_export_env_spec(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         exported = os.path.join(dirname, "exported.yml")
@@ -3546,14 +3549,14 @@ def check(dirname):
         {"anaconda-project.yml": f"""
 env_specs:
   default:
-    {packages}:
+    {pkg_key}:
       - blah
     channels:
       - boo
 """}, check)
 
 
-def test_export_nonexistent_env_spec(packages):
+def test_export_nonexistent_env_spec(pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         exported = os.path.join(dirname, "exported.yml")
@@ -3566,14 +3569,14 @@ def check(dirname):
         {"anaconda-project.yml": f"""
 env_specs:
   default:
-    {packages}:
+    {pkg_key}:
       - blah
     channels:
       - boo
 """}, check)
 
 
-def test_export_env_spec_io_error(monkeypatch, packages):
+def test_export_env_spec_io_error(monkeypatch, pkg_key):
     def check(dirname):
         project = project_no_dedicated_env(dirname)
         exported = os.path.join(dirname, "exported.yml")
@@ -3591,7 +3594,7 @@ def mock_atomic_replace(*args, **kwargs):
         {"anaconda-project.yml": f"""
 env_specs:
   default:
-    {packages}:
+    {pkg_key}:
       - blah
     channels:
       - boo
@@ -3638,7 +3641,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(dict(), check)
 
 
-def test_add_service_with_env_spec(monkeypatch, packages):
+def test_add_service_with_env_spec(monkeypatch, pkg_key):
     def check(dirname):
         _monkeypatch_can_connect_to_socket_on_standard_redis_port(monkeypatch)
 
@@ -3658,10 +3661,10 @@ def check(dirname):
             DEFAULT_PROJECT_FILENAME: f"""
 env_specs:
     default:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
     myspec:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
 """
         }, check)
@@ -3811,7 +3814,7 @@ def check(dirname):
 """}, check)
 
 
-def test_remove_service_with_env_spec(monkeypatch, packages):
+def test_remove_service_with_env_spec(monkeypatch, pkg_key):
     def check(dirname):
         config_path = ['env_specs', 'myspec', 'services', 'REDIS_URL']
         project = project_no_dedicated_env(dirname)
@@ -3829,10 +3832,10 @@ def check(dirname):
             DEFAULT_PROJECT_FILENAME: f"""
 env_specs:
     default:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
     myspec:
-      {packages}: [python]
+      {pkg_key}: [python]
       channels: []
       services:
         REDIS_URL: redis
@@ -4097,7 +4100,7 @@ def check(dirname):
     with_directory_contents_completing_project_file(dict(), archivetest)
 
 
-def test_archive_unlocked_warning(packages):
+def test_archive_unlocked_warning(pkg_key):
     def archivetest(archive_dest_dir):
         archivefile = os.path.join(archive_dest_dir, "foo.zip")
 
@@ -4130,9 +4133,9 @@ def check(dirname):
 name: archivedproj
 env_specs:
   foo:
-    {packages}: []
+    {pkg_key}: []
   bar:
-    {packages}: []
+    {pkg_key}: []
     """,
                 DEFAULT_PROJECT_LOCK_FILENAME: f"""
 locking_enabled: false
@@ -4140,7 +4143,7 @@ def check(dirname):
   foo:
     locked: true
     platforms: [linux-32,linux-64,osx-64,win-32,win-64]
-    {packages}:
+    {pkg_key}:
       all: []
              """,
                 "foo.py": "print('hello')\n"
@@ -4565,7 +4568,7 @@ def check(dirname):
     with_directory_contents(dict(), archivetest)
 
 
-def test_archive_with_unsaved_project(monkeypatch, packages):
+def test_archive_with_unsaved_project(monkeypatch, pkg_key):
     def archivetest(archive_dest_dir):
         archivefile = os.path.join(archive_dest_dir, "foo.zip")
 
@@ -4585,7 +4588,7 @@ def check(dirname):
             {DEFAULT_PROJECT_FILENAME: f"""
 env_specs:
   default:
-    {packages}: []
+    {pkg_key}: []
 """}, check)
 
     with_directory_contents(dict(), archivetest)
@@ -4684,7 +4687,7 @@ def check(dirname):
 @pytest.mark.skipif((sys.version_info.major == 2) and (platform.system() == 'Linux'),
                     reason='Something wrong with pip freeze on linux for py2')
 @pytest.mark.parametrize('suffix', ['zip', 'tar.bz2', 'tar.gz'])
-def test_archive_unarchive_conda_pack_with_pip(suffix, packages):
+def test_archive_unarchive_conda_pack_with_pip(suffix, pkg_key):
     def archivetest(archive_dest_dir):
         archivefile = os.path.join(archive_dest_dir, "foo.{}".format(suffix))
 
@@ -4713,7 +4716,7 @@ def check(dirname):
         with_directory_contents_completing_project_file(
             {DEFAULT_PROJECT_FILENAME: f"""
 name: archivedproj
-{packages}:
+{pkg_key}:
   - python=3.7
   - pip:
     - pep8
@@ -4724,7 +4727,7 @@ def check(dirname):
 
 @pytest.mark.slow
 @pytest.mark.parametrize('suffix', ['zip', 'tar.bz2', 'tar.gz'])
-def test_archive_unarchive_conda_pack(suffix, packages):
+def test_archive_unarchive_conda_pack(suffix, pkg_key):
     def archivetest(archive_dest_dir):
         archivefile = os.path.join(archive_dest_dir, "foo.{}".format(suffix))
 
@@ -4802,7 +4805,7 @@ def check(dirname):
             {
                 DEFAULT_PROJECT_FILENAME: f"""
 name: archivedproj
-{packages}:
+{pkg_key}:
   - font-ttf-ubuntu=0.83=h8b1ccd4_0
         """,
                 "foo.py": "print('hello')\n",
diff --git a/anaconda_project/yaml_file.py b/anaconda_project/yaml_file.py
index b278892e..37584c48 100644
--- a/anaconda_project/yaml_file.py
+++ b/anaconda_project/yaml_file.py
@@ -139,12 +139,10 @@ def __init__(self, filename):
         self._change_count = 0
         self.load()
 
-        # Set `pkg_key` if we have one at the top level of the file, otherwise use
-        # default.  Could look into environments if not defined.  Could also raise error
-        # if both are defined?
-        for pkg_key in ['dependencies', 'packages']:
-            if self.get_value(pkg_key):
-                self.pkg_key = pkg_key
+        pkg_key = self._get_pkg_key()
+        if pkg_key:
+            # Only set if defined, otherwise fallback to the class default.
+            self.pkg_key = pkg_key
 
     def load(self):
         """Reload the file from disk, discarding any unsaved changes.
@@ -207,6 +205,30 @@ def load(self):
                     # pretend we already saved
                     self._previous_content = _dump_string(self._yaml)
 
+    def _get_pkg_key(self):
+        """Return the `pkg_key` ('dependencies' or 'packages') for the file.
+
+        We search for an appropriately named key at the top level, or in the
+        `env_specs`.  Return `None` if none specified.
+        """
+        pkg_key = None
+        try:
+            for _pkg_key in ['dependencies', 'packages']:
+                if self.get_value(_pkg_key):
+                    assert not pkg_key or pkg_key == _pkg_key
+                    pkg_key = _pkg_key
+            env_specs = self.get_value('env_specs')
+            if env_specs:
+                for _spec in env_specs:
+                    for _pkg_key in ['dependencies', 'packages']:
+                        if _pkg_key in env_specs[_spec]:
+                            assert not pkg_key or pkg_key == _pkg_key
+                            pkg_key = _pkg_key
+        except Exception:
+            # Don't do error checking here...
+            pass
+        return pkg_key
+
     def _load_template(self):
         # ruamel.yaml returns None if you load an empty file,
         # so we have to build this ourselves
diff --git a/anaconda_project/test/conftest.py b/conftest.py
similarity index 84%
rename from anaconda_project/test/conftest.py
rename to conftest.py
index 2795de4d..68fb1196 100644
--- a/anaconda_project/test/conftest.py
+++ b/conftest.py
@@ -4,7 +4,7 @@
 
 
 @pytest.fixture(params=["packages", "dependencies"])
-def packages(request):
+def pkg_key(request):
     """Ensure equivalence between `dependencies` and `packages`"""
     yield request.param
 
@@ -14,7 +14,7 @@ def _change_default_pkg_key(test_function):
 
     @functools.wraps(test_function)
     def wrapper(*v, **kw):
-        old_pkg_key, YamlFile.pkg_key = YamlFile.pkg_key, kw['packages']
+        old_pkg_key, YamlFile.pkg_key = YamlFile.pkg_key, kw['pkg_key']
         try:
             return test_function(*v, **kw)
         finally: