diff --git a/core/lib/Drupal/Component/Utility/String.php b/core/lib/Drupal/Component/Utility/String.php
index 0512c32..26e74f9 100644
--- a/core/lib/Drupal/Component/Utility/String.php
+++ b/core/lib/Drupal/Component/Utility/String.php
@@ -335,7 +335,7 @@ protected static function xssAttributes($attr) {
         case 2:
           // Attribute value, a URL after href= for instance.
           if (preg_match('/^"([^"]*)"(\s+|$)/', $attr, $match)) {
-            $thisval = static::filterBadProtocol($match[1]);
+            $thisval = Url::filterBadProtocol($match[1]);
 
             if (!$skip) {
               $attrarr[] = "$attrname=\"$thisval\"";
@@ -347,7 +347,7 @@ protected static function xssAttributes($attr) {
           }
 
           if (preg_match("/^'([^']*)'(\s+|$)/", $attr, $match)) {
-            $thisval = static::filterBadProtocol($match[1]);
+            $thisval = Url::filterBadProtocol($match[1]);
 
             if (!$skip) {
               $attrarr[] = "$attrname='$thisval'";
@@ -358,7 +358,7 @@ protected static function xssAttributes($attr) {
           }
 
           if (preg_match("%^([^\s\"']+)(\s+|$)%", $attr, $match)) {
-            $thisval = static::filterBadProtocol($match[1]);
+            $thisval = Url::filterBadProtocol($match[1]);
 
             if (!$skip) {
               $attrarr[] = "$attrname=\"$thisval\"";