diff --git a/core/lib/Drupal/Core/Language/LanguageManager.php b/core/lib/Drupal/Core/Language/LanguageManager.php
index c0177df..62e16c3 100644
--- a/core/lib/Drupal/Core/Language/LanguageManager.php
+++ b/core/lib/Drupal/Core/Language/LanguageManager.php
@@ -248,7 +248,7 @@ public static function getStandardLanguageList() {
       'dz' => ['Dzongkha', 'རྫོང་ཁ'],
       'el' => ['Greek', 'Ελληνικά'],
       'en' => ['English', 'English'],
-      'en-x-simple' => ['Simple English', 'Simple English'],
+      'enx' => ['Simple English', 'Simple English'],
       'eo' => ['Esperanto', 'Esperanto'],
       'es' => ['Spanish', 'Español'],
       'et' => ['Estonian', 'Eesti'],