diff --git a/phpgwapi/inc/class.html.inc.php b/phpgwapi/inc/class.html.inc.php
index ce9a074c27..bb956a9ef5 100644
--- a/phpgwapi/inc/class.html.inc.php
+++ b/phpgwapi/inc/class.html.inc.php
@@ -67,7 +67,8 @@
 
 		function htmlspecialchars($str)
 		{
-			return htmlspecialchars($str,ENT_COMPAT,$this->charset);
+			// add @ by lkneschke to supress warning about unknown charset
+			return @htmlspecialchars($str,ENT_COMPAT,$this->charset);
 		}
 
 		/*!