diff --git a/admin/admin_ug_auth.php b/admin/admin_ug_auth.php
index 062af1d4..3b89a64d 100644
--- a/admin/admin_ug_auth.php
+++ b/admin/admin_ug_auth.php
@@ -203,7 +203,7 @@ if ($mode == 'user' && (!empty($_POST['username']) || $user_id))
 	if (!empty($_POST['username']))
 	{
 		$this_userdata = get_userdata($_POST['username'], true);
-		$user_id = $this_userdata['user_id'];
+		$user_id = $this_userdata ? $this_userdata['user_id'] : false;
 	}
 	else
 	{