diff --git a/oauth2client/appengine.py b/oauth2client/appengine.py
index 6f63831..aebbd32 100644
--- a/oauth2client/appengine.py
+++ b/oauth2client/appengine.py
@@ -70,7 +70,8 @@
     """Constructor for AppAssertionCredentials
 
     Args:
-      scope: string or list of strings, scope(s) of the credentials being requested.
+      scope: string or list of strings, scope(s) of the credentials being
+        requested.
     """
     if type(scope) is list:
       scope = ' '.join(scope)