diff --git a/core/lib/Drupal/Component/Utility/Unicode.php b/core/lib/Drupal/Component/Utility/Unicode.php
index 94c4bcf..4fe35f9 100644
--- a/core/lib/Drupal/Component/Utility/Unicode.php
+++ b/core/lib/Drupal/Component/Utility/Unicode.php
@@ -554,7 +554,7 @@ public static function truncate($string, $max_length, $wordsafe = FALSE, $add_el
    *   $str2, and 0 if they are equal.
    */
   public static function strCaseCmp($str1 , $str2) {
-    return strcmp(mb_strtoupper($str1, 'utf-8'), mb_strtoupper($str2, 'utf-8'));
+    return strcmp(static::strtoupper($str1), static::strtoupper($str2));
   }
 
   /**