--- a/src/pip/_vendor/pyproject_hooks/_in_process/__init__.py
+++ b/src/pip/_vendor/pyproject_hooks/_in_process/__init__.py
@@ -11,11 +11,17 @@ try:
 except AttributeError:
     # Python 3.8 compatibility
     def _in_proc_script_path():
-        return resources.path(__package__, "_in_process.py")
+        filename = "_in_process.pyc"
+        if resources.is_resource(__package__, "_in_process.py"):
+            filename = "_in_process.py"
+        return resources.path(__package__, filename)
 
 else:
 
     def _in_proc_script_path():
+        filename = "_in_process.pyc"
+        if resources.files(__package__).joinpath("_in_process.py").is_file():
+            filename = "_in_process.py"
         return resources.as_file(
-            resources.files(__package__).joinpath("_in_process.py")
+            resources.files(__package__).joinpath(filename)
         )
