diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 6e0fec07..fb55aa5b 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -25,7 +25,6 @@ repos:
   hooks:
   - id: mypy
     name: mypy 3.11 on cibuildwheel/
-    exclude: ^cibuildwheel/resources/.*py$
     args: ["--python-version=3.11"]
     additional_dependencies: &mypy-dependencies
       - bracex
diff --git a/cibuildwheel/resources/install_certifi.py b/cibuildwheel/resources/install_certifi.py
index 0d261d51..86052175 100644
--- a/cibuildwheel/resources/install_certifi.py
+++ b/cibuildwheel/resources/install_certifi.py
@@ -26,7 +26,7 @@ STAT_0o775 = (
 )
 
 
-def main():
+def main() -> None:
     openssl_dir, openssl_cafile = os.path.split(ssl.get_default_verify_paths().openssl_cafile)
     print(" -- pip install --upgrade certifi")
     subprocess.check_call(