diff --git a/core/lib/Drupal/Component/Utility/Xss.php b/core/lib/Drupal/Component/Utility/Xss.php
index d55b91c..a1f1956 100644
--- a/core/lib/Drupal/Component/Utility/Xss.php
+++ b/core/lib/Drupal/Component/Utility/Xss.php
@@ -188,6 +188,7 @@ protected static function attributes($attributes) {
     $attributes_array = array();
     $mode = 0;
     $attribute_name = '';
+    $skip = FALSE;
 
     while (strlen($attributes) != 0) {
       // Was the last operation successful?