diff --git a/keystoneclient/base.py b/keystoneclient/base.py
index 62d96f143..529e0c3da 100644
--- a/keystoneclient/base.py
+++ b/keystoneclient/base.py
@@ -216,11 +216,10 @@ class Manager(object):
             return self.resource_class(self, body[response_key])
 
 
+@six.add_metaclass(abc.ABCMeta)
 class ManagerWithFind(Manager):
     """Manager with additional `find()`/`findall()` methods."""
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def list(self):
         pass