diff --git a/tests/test_import_all_modules.py b/tests/test_import_all_modules.py
index 1e59215..e1a957e 100644
--- a/tests/test_import_all_modules.py
+++ b/tests/test_import_all_modules.py
@@ -20,7 +20,8 @@ def preserve_sys_path():
 def preserve_sys_modules():
     original_sys_modules = dict(sys.modules)
     yield
-    sys.modules = original_sys_modules
+    sys.modules.clear()
+    sys.modules.update(original_sys_modules)
 
 
 @pytest.mark.parametrize(