diff --git a/plstackapi/core/api/users.py b/plstackapi/core/api/users.py
index 09384f2..18a68c7 100644
--- a/plstackapi/core/api/users.py
+++ b/plstackapi/core/api/users.py
@@ -13,7 +13,7 @@
         if sites:
             site = sites[0]
     if not site:
-        raise Exception, "No such site", fields['site']
+        raise Exception, "No such site: %s" % fields['site']
     return site 
 
 def add_user(auth, fields):