diff --git a/oauth2client/appengine.py b/oauth2client/appengine.py
index 8a24fce..73c48d4 100644
--- a/oauth2client/appengine.py
+++ b/oauth2client/appengine.py
@@ -409,7 +409,7 @@
     user = users.get_current_user()
     memcache.set(user.user_id(), pickle.dumps(self.flow),
                  namespace=OAUTH2CLIENT_NAMESPACE)
-    return url
+    return str(url)
 
   def http(self):
     """Returns an authorized http instance.
diff --git a/setup.py b/setup.py
index b6fee4e..6095d8f 100644
--- a/setup.py
+++ b/setup.py
@@ -30,7 +30,7 @@
   ]
 
 install_requires = [
-    'httplib2>=0.7.2',
+    'httplib2>=0.7.4',
     'oauth2',
     'python-gflags',
     ]