diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityListController.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityListController.php
index 63d8591..4a401a2 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityListController.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityListController.php
@@ -22,7 +22,7 @@ class ConfigEntityListController extends EntityListController implements FormInt
    *
    * @var string|bool
    */
-  protected $weightKey;
+  protected $weightKey = FALSE;
 
   /**
    * {@inheritdoc}
@@ -30,7 +30,6 @@ class ConfigEntityListController extends EntityListController implements FormInt
   public function __construct($entity_type, EntityStorageControllerInterface $storage) {
     parent::__construct($entity_type, $storage);
 
-    $this->weightKey = FALSE;
     // Check if the entity type supports weighting.
     if (!empty($this->entityInfo['entity_keys']['weight'])) {
       $this->weightKey = $this->entityInfo['entity_keys']['weight'];