diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index d76425b688..b10d53c32f 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -563,13 +563,11 @@ function backslashit($string) {
 }
 
 function trailingslashit($string) {
-		if ( '/' != substr($string, -1))
-				$string .= '/';
-		return $string;
+	return untrailingslashit($string) . '/';
 }
 
 function untrailingslashit($string) {
-	return preg_replace('|/+$|', '', $string);
+	return rtrim($string, '/');
 }
 
 function addslashes_gpc($gpc) {