diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index 4ddad797a5..c76396f74c 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -1111,7 +1111,7 @@ function clean_url( $url, $protocols = null, $context = 'display' ) {
 	$original_url = $url;
 
 	if ('' == $url) return $url;
-	$url = preg_replace('|[^a-z0-9-~+_.?#=!&;,/:%@]|i', '', $url);
+	$url = preg_replace('|[^a-z0-9-~+_.?#=!&;,/:%@()]|i', '', $url); 
 	$strip = array('%0d', '%0a');
 	$url = str_replace($strip, '', $url);
 	$url = str_replace(';//', '://', $url);