diff --git a/Lib/test/test_email/test_inversion.py b/Lib/test/test_email/test_inversion.py
index 6f5c5346764..f36e33d4319 100644
--- a/Lib/test/test_email/test_inversion.py
+++ b/Lib/test/test_email/test_inversion.py
@@ -43,3 +43,7 @@ def msg_as_input(self, msg):
             """),),
 
             }
+
+
+if __name__ == '__main__':
+    unittest.main()