diff --git a/core/core.services.yml b/core/core.services.yml
index 2b27f69..6eb32c2 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -520,6 +520,8 @@ services:
     arguments: ['@state']
     tags:
       - { name: event_subscriber }
+  # This service should not be overridden. See
+  # \Drupal\Core\Entity\Query\QueryFactory.
   entity.query:
     class: Drupal\Core\Entity\Query\QueryFactory
     arguments: ['@entity.manager']
diff --git a/core/lib/Drupal/Core/Entity/Query/QueryFactory.php b/core/lib/Drupal/Core/Entity/Query/QueryFactory.php
index 5f1ab13..4a382fd 100644
--- a/core/lib/Drupal/Core/Entity/Query/QueryFactory.php
+++ b/core/lib/Drupal/Core/Entity/Query/QueryFactory.php
@@ -13,8 +13,17 @@
 
 /**
  * Factory class Creating entity query objects.
+ *
+ * This class is marked as final since it should not be overridden in the
+ * container. EntityStorageBase::getQuery() accesses the storages query service
+ * directly without using this factory.
+ *
+ * @see \Drupal\Core\Entity\EntityStorageBase::getQuery()
+ *
+ * @todo https://www.drupal.org/node/2389335 remove entity.query service and
+ *   replace with using the entity storage's getQuery() method.
  */
-class QueryFactory implements ContainerAwareInterface {
+final class QueryFactory implements ContainerAwareInterface {
 
   use ContainerAwareTrait;