diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
index 50b0f3fff04c57..b8f315062b2b90 100644
--- a/Lib/test/test_warnings/__init__.py
+++ b/Lib/test/test_warnings/__init__.py
@@ -93,7 +93,8 @@ def test_module_all_attribute(self):
         self.assertTrue(hasattr(self.module, '__all__'))
         target_api = ["warn", "warn_explicit", "showwarning",
                       "formatwarning", "filterwarnings", "simplefilter",
-                      "resetwarnings", "catch_warnings", "deprecated"]
+                      "resetwarnings", "catch_warnings", "deprecated",
+                      "WarningMessage"]
         self.assertSetEqual(set(self.module.__all__),
                             set(target_api))