diff --git a/authentication.php b/authentication.php
index 48ee381..62d3bf0 100644
--- a/authentication.php
+++ b/authentication.php
@@ -98,7 +98,7 @@ class authentication
     unset ($_SESSION["domframework"]["authentication"]);
     if ($this->debug) echo "Redirect to authentication page";
     if ($this->debug) $this->route->debug = $this->debug;
-    if ($url === "")
+    if ($url === "" || $url === null)
     {
       $_SESSION["domframework"]["authentication"]["message"] =
          dgettext("domframework", "You have been logged out");