diff -Naur a/include/html_main.inc.php b/include/html_main.inc.php
--- a/include/html_main.inc.php	2013-10-18 00:10:50.000000000 +0200
+++ b/include/html_main.inc.php	2014-11-09 18:09:00.019001604 +0100
@@ -344,3 +344,6 @@
     }
 }
 
+function session_unregister($name) {
+    unset($_SESSION[$name]);
+}