diff --git a/framework/base/Controller.php b/framework/base/Controller.php
index 8852d8a4672..a90150d058d 100644
--- a/framework/base/Controller.php
+++ b/framework/base/Controller.php
@@ -50,7 +50,7 @@ class Controller extends Component implements ViewContextInterface
      */
     public $defaultAction = 'index';
     /**
-     * @var string|boolean the name of the layout to be applied to this controller's views.
+     * @var null|string|boolean the name of the layout to be applied to this controller's views.
      * This property mainly affects the behavior of [[render()]].
      * Defaults to null, meaning the actual layout value should inherit that from [[module]]'s layout value.
      * If false, no layout will be applied.