diff --git a/core/lib/Drupal/Core/Entity/DraggableListBuilderTrait.php b/core/lib/Drupal/Core/Entity/DraggableListBuilderTrait.php
index 5ccbbde2d2e09127e422504a60b9bd6e5f53a23a..472f774a75c72b4993b7a8765037bd7745cb5066 100644
--- a/core/lib/Drupal/Core/Entity/DraggableListBuilderTrait.php
+++ b/core/lib/Drupal/Core/Entity/DraggableListBuilderTrait.php
@@ -7,8 +7,8 @@
 /**
  * Provides a trait for draggable listings of entities.
  *
- * Classes using this trait are expected to set the $formBuilder property in
- * their constructor.
+ * Classes using this trait must implement \Drupal\Core\Form\FormInterface and
+ * are expected to set the $formBuilder property in their constructor.
  */
 trait DraggableListBuilderTrait {