diff -urpN a/Lib/types.py b/Lib/types.py
--- a/Lib/types.py	2014-05-18 22:19:39.000000000 -0700
+++ b/Lib/types.py	2014-11-29 11:55:05.131180321 -0800
@@ -88,9 +88,9 @@ def _calculate_meta(meta, bases):
     winner = meta
     for base in bases:
         base_meta = type(base)
-        if issubclass(winner, base_meta):
+        if type.__subclasscheck__(base_meta, winner):
             continue
-        if issubclass(base_meta, winner):
+        if type.__subclasscheck__(winner, base_meta):
             winner = base_meta
             continue
         # else: