diff --git a/core/modules/forum/forum.module b/core/modules/forum/forum.module
index f446c49..60f301c 100644
--- a/core/modules/forum/forum.module
+++ b/core/modules/forum/forum.module
@@ -74,7 +74,7 @@ function forum_theme() {
   return array(
     'forums' => array(
       'template' => 'forums',
-      'variables' => array('forums' => array(), 'topics' => array(), 'topics_pager' => array(), 'parents' => NULL, 'term' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL),
+      'variables' => array('forums' => array(), 'topics' => array(), 'topics_pager' => array(), 'parents' => NULL, 'term' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL, 'header' => array()),
     ),
     'forum_list' => array(
       'template' => 'forum-list',
@@ -657,7 +657,7 @@ function template_preprocess_forums(&$variables) {
     }
 
     if ($variables['term'] && empty($variables['term']->forum_container->value) && !empty($variables['topics'])) {
-      $forum_topic_list_header = \Drupal::service('forum.manager')->getHeader();
+      $forum_topic_list_header = $variables['header'];
 
       $table = array(
         '#theme' => 'table__forum_topic_list',
diff --git a/core/modules/forum/lib/Drupal/forum/Controller/ForumController.php b/core/modules/forum/lib/Drupal/forum/Controller/ForumController.php
index e982429..d503cdb 100644
--- a/core/modules/forum/lib/Drupal/forum/Controller/ForumController.php
+++ b/core/modules/forum/lib/Drupal/forum/Controller/ForumController.php
@@ -82,12 +82,15 @@ public function forumPage(TermInterface $taxonomy_term) {
     $taxonomy_term->parents = $this->forumManager->getParents($taxonomy_term->id());
 
     if (empty($taxonomy_term->forum_container->value)) {
-      $topics = $this->forumManager->getTopics($taxonomy_term->id());
+      $build = $this->forumManager->getTopics($taxonomy_term->id());
+      $topics = $build['topics'];
+      $header = $build['header'];
     }
     else {
       $topics = '';
+      $header = array();
     }
-    return $this->build($taxonomy_term->forums, $taxonomy_term, $topics, $taxonomy_term->parents);
+    return $this->build($taxonomy_term->forums, $taxonomy_term, $topics, $taxonomy_term->parents, $header);
   }
 
   /**
@@ -122,17 +125,20 @@ public function forumIndex() {
    *   The topics of this forum.
    * @param array $parents
    *   The parent forums in relation this forum.
+   * @param array $header
+   *   Array of header cells.
    *
    * @return array
    *   A render array.
    */
-  protected function build($forums, TermInterface $term, $topics = array(), $parents = array()) {
+  protected function build($forums, TermInterface $term, $topics = array(), $parents = array(), $header = array()) {
     $config = $this->config('forum.settings');
     $build = array(
       '#theme' => 'forums',
       '#forums' => $forums,
       '#topics' => $topics,
       '#parents' => $parents,
+      '#header' => $header,
       '#term' => $term,
       '#sortby' => $config->get('topics.order'),
       '#forums_per_page' => $config->get('topics.page_limit'),
diff --git a/core/modules/forum/lib/Drupal/forum/ForumManager.php b/core/modules/forum/lib/Drupal/forum/ForumManager.php
index 0805bf8..a5ba96b 100644
--- a/core/modules/forum/lib/Drupal/forum/ForumManager.php
+++ b/core/modules/forum/lib/Drupal/forum/ForumManager.php
@@ -97,13 +97,6 @@ class ForumManager implements ForumManagerInterface {
   protected $index;
 
   /**
-   * Cached table header.
-   *
-   * @var array
-   */
-  protected $header;
-
-  /**
    * Field info service.
    *
    * @var \Drupal\field\FieldInfo
@@ -149,16 +142,16 @@ public function getTopics($tid) {
 
     $user = \Drupal::currentUser();
 
-    $this->header = array(
+    $header = array(
       array('data' => $this->t('Topic'), 'field' => 'f.title'),
       array('data' => $this->t('Replies'), 'field' => 'f.comment_count'),
       array('data' => $this->t('Last reply'), 'field' => 'f.last_comment_timestamp'),
     );
 
     $order = $this->getTopicOrder($sortby);
-    for ($i = 0; $i < count($this->header); $i++) {
-      if ($this->header[$i]['field'] == $order['field']) {
-        $this->header[$i]['sort'] = $order['sort'];
+    for ($i = 0; $i < count($header); $i++) {
+      if ($header[$i]['field'] == $order['field']) {
+        $header[$i]['sort'] = $order['sort'];
       }
     }
 
@@ -171,7 +164,7 @@ public function getTopics($tid) {
       ->addTag('node_access')
       ->addMetaData('base_table', 'forum_index')
       ->orderBy('f.sticky', 'DESC')
-      ->orderByHeader($this->header)
+      ->orderByHeader($header)
       ->limit($forum_per_page);
 
     $count_query = $this->connection->select('forum_index', 'f');
@@ -213,7 +206,7 @@ public function getTopics($tid) {
 
       $query
         ->orderBy('f.sticky', 'DESC')
-        ->orderByHeader($this->header)
+        ->orderByHeader($header)
         ->condition('n.nid', $nids)
         // @todo This should be actually filtering on the desired node language
         //   and just fall back to the default language.
@@ -272,7 +265,7 @@ public function getTopics($tid) {
       $topics[$topic->id()] = $topic;
     }
 
-    return $topics;
+    return array('topics' => $topics, 'header' => $header);
 
   }
 
@@ -566,11 +559,4 @@ protected function t($string, array $args = array(), array $options = array()) {
     return $this->translationManager->translate($string, $args, $options);
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function getHeader() {
-    return $this->header;
-  }
-
 }
diff --git a/core/modules/forum/lib/Drupal/forum/ForumManagerInterface.php b/core/modules/forum/lib/Drupal/forum/ForumManagerInterface.php
index 48cdd3b..cdcfb38 100644
--- a/core/modules/forum/lib/Drupal/forum/ForumManagerInterface.php
+++ b/core/modules/forum/lib/Drupal/forum/ForumManagerInterface.php
@@ -21,7 +21,7 @@
    *   Term ID.
    *
    * @return array
-   *   Array of topics.
+   *   Array with keys 'topics' and 'header'.
    */
   public function getTopics($tid);
 
@@ -101,12 +101,4 @@ public function unreadTopics($term, $uid);
    */
   public function updateIndex($nid);
 
-  /**
-   * Returns the topic list header.
-   *
-   * @return array
-   *   Array representing the table list header.
-   */
-  public function getHeader();
-
 }