diff --git a/lib/functions.php b/lib/functions.php
index 19fde99..eb160dc 100644
--- a/lib/functions.php
+++ b/lib/functions.php
@@ -1003,8 +1003,9 @@ function masort(&$data,$sortby,$rev=0) {
 	if (defined('DEBUG_ENABLED') && DEBUG_ENABLED && (($fargs=func_get_args())||$fargs='NOARGS'))
 		debug_log('Entered (%%)',1,0,__FILE__,__LINE__,__METHOD__,$fargs);
 
-	# if the array to sort is null or empty
-	if (! $data) return;
+	# if the array to sort is null or empty, or if we have some nasty chars
+	if (! preg_match('/^[a-zA-Z0-9_]+(\([a-zA-Z0-9_,]*\))?$/',$sortby) || ! $data)
+		return;
 
 	static $CACHE = array();