diff --git a/core/modules/views/src/ManyToOneHelper.php b/core/modules/views/src/ManyToOneHelper.php
index 6d47212a89..1586625fae 100644
--- a/core/modules/views/src/ManyToOneHelper.php
+++ b/core/modules/views/src/ManyToOneHelper.php
@@ -20,6 +20,13 @@
  */
 class ManyToOneHelper {
 
+  /**
+   * The handler.
+   *
+   * @var Drupal\views\Plugin\views\ViewsHandlerInterface
+   */
+  protected $handler;
+
   public function __construct($handler) {
     $this->handler = $handler;
   }