diff --git a/actions/login.php b/actions/login.php
index ad57dd6678..881df0099a 100644
--- a/actions/login.php
+++ b/actions/login.php
@@ -146,7 +146,7 @@ class LoginAction extends Action
 
         // success!
         if (!common_set_user($user)) {
-            $this->serverError(_('Error setting user.'));
+            $this->serverError(_('Error setting user. You are probably not authorized.'));
             return;
         }