diff --git a/keystonemiddleware/auth_token/__init__.py b/keystonemiddleware/auth_token/__init__.py
index 0db3b04a..96823fd7 100644
--- a/keystonemiddleware/auth_token/__init__.py
+++ b/keystonemiddleware/auth_token/__init__.py
@@ -407,7 +407,7 @@ class BaseAuthProtocol(object):
         :returns: The token data
         :rtype: dict
         """
-        raise NotImplemented()
+        raise NotImplementedError()
 
     def process_response(self, response):
         """Do whatever you'd like to the response.