diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Form/CategorizeFormBase.php b/core/modules/aggregator/lib/Drupal/aggregator/Form/CategorizeFormBase.php
index 8e4aa70..f0e1b7c 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Form/CategorizeFormBase.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Form/CategorizeFormBase.php
@@ -12,16 +12,15 @@
 use Drupal\aggregator\ItemStorageControllerInterface;
 use Drupal\Component\Utility\String;
 use Drupal\Core\Config\Config;
-use Drupal\Core\Controller\ControllerInterface;
 use Drupal\Core\Database\Connection;
 use Drupal\Core\Entity\EntityRenderControllerInterface;
-use Drupal\Core\Form\FormInterface;
+use Drupal\Core\Form\FormBase;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Provides a base form to allow items to be categorized.
  */
-abstract class CategorizeFormBase implements FormInterface, ControllerInterface {
+abstract class CategorizeFormBase extends FormBase {
 
   /**
    * The aggregator item render controller.
@@ -171,10 +170,4 @@ public function submitForm(array &$form, array &$form_state) {
     drupal_set_message(t('The categories have been saved.'));
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function validateForm(array &$form, array &$form_state) {
-  }
-
 }