diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8729f14e..1c9fb821 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -65,6 +65,9 @@ jobs:
           - name: '3.12'
             tox_env: integration-py312
 
+          - name: '3.13'
+            tox_env: integration-py313
+
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -73,6 +76,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.py_version.name }}
+          allow-prereleases: true
 
       - name: Install tox
         run: |
@@ -122,6 +126,9 @@ jobs:
           - name: '3.12'
             tox_env: unit-py312
 
+          - name: '3.13'
+            tox_env: unit-py313
+
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -130,6 +137,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.py_version.name }}
+          allow-prereleases: true
 
       - name: Install tox
         run: |
diff --git a/src/ansible_runner/utils/base64io.py b/src/ansible_runner/utils/base64io.py
index 0a2422f1..6a65b5ab 100644
--- a/src/ansible_runner/utils/base64io.py
+++ b/src/ansible_runner/utils/base64io.py
@@ -78,6 +78,10 @@ def __init__(self, wrapped: IO) -> None:
 
         :raises TypeError: if ``wrapped`` does not have attributes needed to determine the stream's state
         """
+        # set before the attr check as we may reach close() after that check fails
+        self.__read_buffer = b""
+        self.__write_buffer = b""
+
         required_attrs = ("read", "write", "close", "closed", "flush")
         if not all(hasattr(wrapped, attr) for attr in required_attrs):
             raise TypeError(
@@ -85,8 +89,6 @@ def __init__(self, wrapped: IO) -> None:
             )
         super().__init__()
         self.__wrapped = wrapped
-        self.__read_buffer = b""
-        self.__write_buffer = b""
 
     def __enter__(self):
         """Return self on enter."""
diff --git a/test/integration/test_transmit_worker_process.py b/test/integration/test_transmit_worker_process.py
index 540e5dc6..cc70a6ac 100644
--- a/test/integration/test_transmit_worker_process.py
+++ b/test/integration/test_transmit_worker_process.py
@@ -193,7 +193,7 @@ def test_keepalive_setting(self, tmp_path, project_fixtures, keepalive_setting):
                 pytest.fail(f'unparseable JSON in output (likely corrupted by keepalive): {line}')
         else:
             # account for some wobble in the number of keepalives for artifact gather, etc
-            assert 1 <= incoming_data.count('"event": "keepalive"') < 5
+            assert 1 <= incoming_data.count('"event": "keepalive"') < 15
 
     @pytest.mark.parametrize("job_type", ['run', 'adhoc'])
     def test_remote_job_by_sockets(self, tmp_path, project_fixtures, job_type):
diff --git a/test/requirements.txt b/test/requirements.txt
index 565292c1..7ab8f9fc 100644
--- a/test/requirements.txt
+++ b/test/requirements.txt
@@ -8,4 +8,6 @@ pytest-xdist==2.5.0
 types-pyyaml
 flake8==6.1.0
 yamllint==1.32.0
+# cffi pre-release to make cryptography work with python 3.13 (remove when 3.13 is released)
+cffi==1.17.0rc1; python_version == "3.13"
 cryptography
diff --git a/tox.ini b/tox.ini
index ef540923..fcd81cbb 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,17 +13,17 @@ deps = ansible27: ansible<2.8
        ansible28: ansible<2.9
        ansible29: ansible<2.10
        ansible-base: ansible-base
-       py{,3,39,310,311}: ansible-core
-       integration{,-py39,-py310,-py311,-py312}: ansible-core
-                                                 build
-                                                 -r {toxinidir}/test/requirements.txt
+       py{,3,39,310,311,312,313}: ansible-core
+       integration{,-py39,-py310,-py311,-py312,-py313}: ansible-core
+                                                        build
+                                                        -r {toxinidir}/test/requirements.txt
 passenv =
     HOME
     RUNNER_TEST_IMAGE_NAME
 usedevelop = True
 commands = pytest -vv -n auto {posargs}
 
-[testenv:linters{,-py39,-py310,-py311,-py312}]
+[testenv:linters{,-py39,-py310,-py311,-py312,-py313}]
 description = Run code linters
 commands =
     flake8 --version
@@ -33,13 +33,14 @@ commands =
     mypy src/ansible_runner
     pylint src/ansible_runner test
 
-[testenv:unit{,-py39,-py310,-py311,-py312}]
+[testenv:unit{,-py39,-py310,-py311,-py312,-py313}]
 description = Run unit tests
 commands = pytest -vv -n auto {posargs:test/unit} {[shared]pytest_cov_args}
 
-[testenv:integration{,-py39,-py310,-py311,-py312}]
+[testenv:integration{,-py39,-py310,-py311,-py312,-py313}]
 description = Run integration tests
-commands = pytest -vv -n auto {posargs:test/integration} {[shared]pytest_cov_args}
+commands =
+    pytest -vv -n auto {posargs:test/integration} {[shared]pytest_cov_args}
 
 [testenv:docs]
 description = Build documentation