diff --git a/core/modules/forum/src/ForumManager.php b/core/modules/forum/src/ForumManager.php
index cac2389..13e5723 100644
--- a/core/modules/forum/src/ForumManager.php
+++ b/core/modules/forum/src/ForumManager.php
@@ -23,8 +23,7 @@
 class ForumManager implements ForumManagerInterface, \Serializable {
   use StringTranslationTrait;
   use DependencySerializationTrait {
-    __wakeup as defaultWakeup;
-    __sleep as defaultSleep;
+    serialize as traitSerialize;
   }
 
   /**
@@ -498,24 +497,10 @@ public function unreadTopics($term, $uid) {
   /**
    * {@inheritdoc}
    */
-  public function __sleep() {
-    $vars = $this->defaultSleep();
+  public function serialize() {
     // Do not serialize static cache.
-    unset($vars['history'], $vars['index'], $vars['lastPostData'], $vars['forumChildren'], $vars['forumStatistics']);
-    return $vars;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function __wakeup() {
-    $this->defaultWakeup();
-    // Initialize static cache.
-    $this->history = array();
-    $this->lastPostData = array();
-    $this->forumChildren = array();
-    $this->forumStatistics = array();
-    $this->index = NULL;
+    unset($this->history, $this->index, $this->lastPostData, $this->forumChildren, $this->forumStatistics);
+    return $this->traitSerialize();
   }
 
 }