diff --git a/src/milla/auth/__init__.py b/src/milla/auth/__init__.py
index 8909fab..daeb535 100644
--- a/src/milla/auth/__init__.py
+++ b/src/milla/auth/__init__.py
@@ -37,7 +37,7 @@ class NotAuthorized(Exception):
         All other arguments and keywords are ignored.
         '''
         
-        response = request.ResponseClass(unicode(self))
+        response = request.ResponseClass(str(self))
         response.status_int = 403
         return response