diff --git a/core/modules/language/language.module b/core/modules/language/language.module
index 4729316..9a91adc 100644
--- a/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -293,25 +293,6 @@ function language_negotiation_url_prefixes() {
 }
 
 /**
- * Update the list of prefixes from the installed languages.
- */
-function language_negotiation_url_prefixes_update() {
-  $config = \Drupal::configFactory()->getEditable('language.negotiation');
-  $prefixes = $config->get('url.prefixes');
-  foreach (\Drupal::languageManager()->getLanguages() as $language) {
-    // The prefix for this language should be updated if it's not assigned yet
-    // or the prefix is set to the empty string.
-    if (empty($prefixes[$language->getId()])) {
-      // For the default language, set the prefix to the empty string,
-      // otherwise use the langcode.
-      $prefixes[$language->getId()] = $language->isDefault() ? '' : $language->getId();
-    }
-    // Otherwise we keep the configured prefix.
-  }
-  $config->set('url.prefixes', $prefixes)->save();
-}
-
-/**
  * Reads language domains.
  *
  * @deprecated in Drupal 8.0.x-dev, will be removed before Drupal 9.0.0.
diff --git a/core/modules/language/src/Entity/ConfigurableLanguage.php b/core/modules/language/src/Entity/ConfigurableLanguage.php
index 89cc167..a153423 100644
--- a/core/modules/language/src/Entity/ConfigurableLanguage.php
+++ b/core/modules/language/src/Entity/ConfigurableLanguage.php
@@ -133,7 +133,7 @@ public function postSave(EntityStorageInterface $storage, $update = TRUE) {
 
     // Update URL Prefixes for all languages after the
     // LanguageManagerInterface::getLanguages() cache is flushed.
-    language_negotiation_url_prefixes_update();
+    self::updateAllUrlPrefixes();
 
     // If after adding this language the site will become multilingual, we need
     // to rebuild language services.
@@ -266,4 +266,23 @@ public static function createFromLangcode($langcode) {
     }
   }
 
+  /**
+   * Update the list of prefixes from the installed languages.
+   */
+  static function updateAllUrlPrefixes() {
+    $config = \Drupal::configFactory()->getEditable('language.negotiation');
+    $prefixes = $config->get('url.prefixes');
+    foreach (\Drupal::languageManager()->getLanguages() as $language) {
+      // The prefix for this language should be updated if it's not assigned yet
+      // or the prefix is set to the empty string.
+      if (empty($prefixes[$language->getId()])) {
+        // For the default language, set the prefix to the empty string,
+        // otherwise use the langcode.
+        $prefixes[$language->getId()] = $language->isDefault() ? '' : $language->getId();
+      }
+      // Otherwise we keep the configured prefix.
+    }
+    $config->set('url.prefixes', $prefixes)->save();
+  }
+
 }
diff --git a/core/modules/language/src/EventSubscriber/ConfigSubscriber.php b/core/modules/language/src/EventSubscriber/ConfigSubscriber.php
index e1875ce..ccfd3dd 100644
--- a/core/modules/language/src/EventSubscriber/ConfigSubscriber.php
+++ b/core/modules/language/src/EventSubscriber/ConfigSubscriber.php
@@ -80,8 +80,7 @@ public function onConfigSave(ConfigCrudEvent $event) {
         $this->languageDefault->set(new Language($default_language->get()));
         $this->languageManager->reset();
 
-        // Directly update language negotiation settings instead of calling
-        // language_negotiation_url_prefixes_update() to ensure that the code
+        // Directly update language negotiation settings to ensure that the code
         // obeys the hook_update_N() restrictions.
         $negotiation_config = $this->configFactory->getEditable('language.negotiation');
         $negotiation_changed = FALSE;