diff --git a/Lib/urllib2.py b/Lib/urllib2.py
index e108b29d337..a2a7e66c837 100644
--- a/Lib/urllib2.py
+++ b/Lib/urllib2.py
@@ -441,7 +441,7 @@ def build_opener(*handlers):
     """
     import types
     def isclass(obj):
-        return isinstance(obj, types.ClassType) or hasattr(obj, "__bases__")
+        return isinstance(obj, (types.ClassType, type))
 
     opener = OpenerDirector()
     default_classes = [ProxyHandler, UnknownHandler, HTTPHandler,