diff --git a/include/functions.inc.php b/include/functions.inc.php
index 2f15b17b0..20ecf5468 100644
--- a/include/functions.inc.php
+++ b/include/functions.inc.php
@@ -361,7 +361,7 @@ function getStudiensemesterFromDatum($datum, $naechstes=true)
 // ****************************************************************
 function checkalias($alias)
 {
-	if(preg_match("/^[-a-z0-9]*[a-z0-9]{1,}\.[-a-z0-9]{1,}$/",$alias))
+	if(preg_match("/^[-a-z0-9\_\.]*[a-z0-9]{1,}\.[-a-z0-9\_]{1,}$/",$alias))
 		return true;
 	else
 		return false;