diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Form/CategorizeFormBase.php b/core/modules/aggregator/lib/Drupal/aggregator/Form/CategorizeFormBase.php
index f0e1b7c..564adf7 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Form/CategorizeFormBase.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Form/CategorizeFormBase.php
@@ -102,7 +102,7 @@ protected function prepareFormItems(array $items, FeedInterface $feed = NULL) {
 
     $form['items'] = array(
       '#type' => 'table',
-      '#header' => array('', t('Categorize')),
+      '#header' => array('', $this->t('Categorize')),
     );
     if ($items && ($form_items = $this->aggregatorItemRenderer->viewMultiple($items, 'default'))) {
       foreach (element_children($form_items) as $iid) {
@@ -167,7 +167,7 @@ public function submitForm(array &$form, array &$form_state) {
         }
       }
     }
-    drupal_set_message(t('The categories have been saved.'));
+    drupal_set_message($this->t('The categories have been saved.'));
   }
 
 }