diff --git a/.github/workflows/pypi.yml b/.github/workflows/pypi.yml
index c3b87d2..5870396 100644
--- a/.github/workflows/pypi.yml
+++ b/.github/workflows/pypi.yml
@@ -20,9 +20,10 @@ jobs:
       - name: Build wheels
         uses: pypa/cibuildwheel@v2.16.2
         env:
-          CIBW_BEFORE_BUILD_LINUX: "pip install --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple numpy meson-python ninja setuptools build"
-          CIBW_BEFORE_BUILD_WINDOWS: "pip install --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple numpy meson-python ninja setuptools build"
-          CIBW_BEFORE_BUILD_MACOS: "pip install --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple numpy meson-python ninja setuptools build"
+          CIBW_PROJECT_REQUIRES_PYTHON: ">=3.7"
+          CIBW_BEFORE_BUILD_LINUX: "pip install numpy meson-python ninja setuptools build"
+          CIBW_BEFORE_BUILD_WINDOWS: "pip install numpy meson-python ninja setuptools build"
+          CIBW_BEFORE_BUILD_MACOS: "pip install numpy meson-python ninja setuptools build"
           CIBW_TEST_REQUIRES: pytest
           CIBW_TEST_COMMAND: pytest stripy
         #    ...
diff --git a/pyproject.toml b/pyproject.toml
index fecdfdf..797cbec 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -22,11 +22,10 @@ maintainers = [
   {name = "Ben Mather", email = "ben.mather@sydney.edu.au"},
 ]
 license = { file = "COPYING.LESSER" }
+requires-python = ">=3.7"
 classifiers = [
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.5",
-    "Programming Language :: Python :: 3.6",
     "Programming Language :: Python :: 3.7",
     "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",