diff --git a/config/func.inc.php b/config/func.inc.php
index bae91b4c7..c57711b21 100644
--- a/config/func.inc.php
+++ b/config/func.inc.php
@@ -742,7 +742,7 @@
 		if($close_tag) $val .= ' /';
 		
 		// attribute on* remove
-		if(preg_match('/^on([a-z]+)/',preg_replace('/[^a-zA-Z_]/','',$key))) return '';
+		if(preg_match('/^on([a-z]+)/i',preg_replace('/[^a-zA-Z_]/','',$key))) return '';
        
 		$output = sprintf('%s=%s', $key, $val);