diff --git a/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageController.php b/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageController.php
index 299113c..aad6ae2 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageController.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageController.php
@@ -98,4 +98,11 @@ public function isUnique($title, $cid = NULL) {
     return (empty($rows));
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function loadByItem($item_id) {
+    return $this->database->query('SELECT c.cid, c.title, ci.iid FROM {aggregator_category} c LEFT JOIN {aggregator_category_item} ci ON c.cid = ci.cid AND ci.iid = :iid', array(':iid' => $item_id));
+  }
+
 }
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageControllerInterface.php b/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageControllerInterface.php
index a4ab4db..90fb48f 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageControllerInterface.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageControllerInterface.php
@@ -66,5 +66,16 @@ public function delete($cid);
    */
   public function isUnique($title, $cid = NULL);
 
+  /**
+   * Loads aggregator categories for an aggregator item.
+   *
+   * @param int $item_id
+   *   The aggregator item ID.
+   *
+   * @return array
+   *   An array of objects containing item ID, category ID and title.
+   */
+  public function loadByItem($item_id);
+
 }
 
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Form/AggregatorCategorizeFormBase.php b/core/modules/aggregator/lib/Drupal/aggregator/Form/AggregatorCategorizeFormBase.php
index 74f4347..e73f684 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Form/AggregatorCategorizeFormBase.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Form/AggregatorCategorizeFormBase.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\aggregator\Form;
 
+use Drupal\aggregator\CategoryStorageControllerInterface;
 use Drupal\aggregator\FeedInterface;
 use Drupal\aggregator\ItemStorageControllerInterface;
 use Drupal\Component\Utility\String;
@@ -50,6 +51,13 @@
   protected $aggregatorItemStorage;
 
   /**
+   * The aggregator category storage controller.
+   *
+   * @var \Drupal\aggregator\CategoryStorageControllerInterface
+   */
+  protected $categoryStorage;
+
+  /**
    * The feed to use.
    *
    * @var \Drupal\aggregator\FeedInterface
@@ -68,11 +76,12 @@
    * @param \Drupal\aggregator\ItemStorageControllerInterface $aggregator_item_storage
    *   The aggregator item storage controller.
    */
-  public function __construct(EntityRenderControllerInterface $aggregator_item_renderer, Connection $database, Config $config, ItemStorageControllerInterface $aggregator_item_storage) {
+  public function __construct(EntityRenderControllerInterface $aggregator_item_renderer, Connection $database, Config $config, ItemStorageControllerInterface $aggregator_item_storage, CategoryStorageControllerInterface $category_storage) {
     $this->aggregatorItemRenderer = $aggregator_item_renderer;
     $this->database = $database;
     $this->config = $config;
     $this->aggregatorItemStorage = $aggregator_item_storage;
+    $this->categoryStorage = $category_storage;
   }
 
   /**
@@ -83,7 +92,8 @@ public static function create(ContainerInterface $container) {
       $container->get('plugin.manager.entity')->getRenderController('aggregator_item'),
       $container->get('database'),
       $container->get('config.factory')->get('aggregator.settings'),
-      $container->get('plugin.manager.entity')->getStorageController('aggregator_item')
+      $container->get('plugin.manager.entity')->getStorageController('aggregator_item'),
+      $container->get('aggregator.category.storage')
     );
   }
 
@@ -104,7 +114,7 @@ public function buildForm(array $form, array &$form_state, array $items = NULL)
     );
     if ($items && ($form_items = $this->aggregatorItemRenderer->viewMultiple($items, 'default'))) {
       foreach (element_children($form_items) as $iid) {
-        $categories_result = $this->database->query('SELECT c.cid, c.title, ci.iid FROM {aggregator_category} c LEFT JOIN {aggregator_category_item} ci ON c.cid = ci.cid AND ci.iid = :iid', array(':iid' => $iid));
+        $categories_result = $this->categoryStorage->loadByItem($iid);
 
         $selected = array();
         foreach ($categories_result as $category) {