diff --git a/Lib/UserDict.py b/Lib/UserDict.py
index df5f7fbe49e..0497f65d1db 100644
--- a/Lib/UserDict.py
+++ b/Lib/UserDict.py
@@ -13,6 +13,7 @@ class UserDict(object):
             return cmp(self.data, dict.data)
         else:
             return cmp(self.data, dict)
+    __hash__ = None # Avoid Py3k warning
     def __len__(self): return len(self.data)
     def __getitem__(self, key):
         if key in self.data: