diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 86a5a3dfebd..1adfcf92579 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -1694,6 +1694,7 @@ _non_defaults = {
     '__reduce__', '__reduce_ex__', '__getinitargs__', '__getnewargs__',
     '__getstate__', '__setstate__', '__getformat__', '__setformat__',
     '__repr__', '__dir__', '__subclasses__', '__format__',
+    '__getnewargs_ex__',
 }