diff --git a/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageController.php b/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageController.php
index aad6ae2..7a39a98 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageController.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageController.php
@@ -105,4 +105,24 @@ 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));
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function updateCategoriesForItem($iid, array $cids) {
+    // Remove all existing category items.
+    $this->database->delete('aggregator_category_item')
+      ->condition('iid', $iid)
+      ->execute();
+
+    // Insert new category items.
+    if (!empty($cids)) {
+      $insert = $this->database->insert('aggregator_category_item')
+        ->fields(array('iid', 'cid'));
+      foreach ($cids as $cid) {
+        $insert->values(array('iid' => $iid, 'cid' => $cid));
+      }
+      $insert->execute();
+    }
+  }
+
 }
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageControllerInterface.php b/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageControllerInterface.php
index 90fb48f..cd52660 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageControllerInterface.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/CategoryStorageControllerInterface.php
@@ -77,5 +77,15 @@ public function isUnique($title, $cid = NULL);
    */
   public function loadByItem($item_id);
 
+  /**
+   * Updates the categories for an aggregator item.
+   *
+   * @param int $iid
+   *   The aggregator item ID.
+   * @param array $cids
+   *   The category IDs.
+   */
+  public function updateCategoriesForItem($iid, array $cids);
+
 }
 
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Form/AggregatorCategorizeFormBase.php b/core/modules/aggregator/lib/Drupal/aggregator/Form/AggregatorCategorizeFormBase.php
index e73f684..eaf4e9f 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Form/AggregatorCategorizeFormBase.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Form/AggregatorCategorizeFormBase.php
@@ -12,7 +12,6 @@
 use Drupal\aggregator\ItemStorageControllerInterface;
 use Drupal\Component\Utility\String;
 use Drupal\Core\Config\Config;
-use Drupal\Core\Database\Connection;
 use Drupal\Core\Entity\EntityRenderControllerInterface;
 use Drupal\Core\Form\FormBase;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -37,13 +36,6 @@
   protected $config;
 
   /**
-   * The database connection.
-   *
-   * @var \Drupal\Core\Database\Connection;
-   */
-  protected $database;
-
-  /**
    * The aggregator item storage controller.
    *
    * @var \Drupal\aggregator\ItemStorageControllerInterface
@@ -69,16 +61,15 @@
    *
    * @param \Drupal\Core\Entity\EntityRenderControllerInterface $aggregator_item_renderer
    *   The item render controller.
-   * @param \Drupal\Core\Database\Connection $database
-   *   The database connection.
    * @param \Drupal\Core\Config\Config $config
    *   The aggregator config.
    * @param \Drupal\aggregator\ItemStorageControllerInterface $aggregator_item_storage
    *   The aggregator item storage controller.
+   * @param \Drupal\aggregator\CategoryStorageControllerInterface $category_storage
+   *   The category storage controller.
    */
-  public function __construct(EntityRenderControllerInterface $aggregator_item_renderer, Connection $database, Config $config, ItemStorageControllerInterface $aggregator_item_storage, CategoryStorageControllerInterface $category_storage) {
+  public function __construct(EntityRenderControllerInterface $aggregator_item_renderer, 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;
@@ -90,7 +81,6 @@ public function __construct(EntityRenderControllerInterface $aggregator_item_ren
   public static function create(ContainerInterface $container) {
     return new static(
       $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('aggregator.category.storage')
@@ -154,25 +144,8 @@ public function buildForm(array $form, array &$form_state, array $items = NULL)
    */
   public function submitForm(array &$form, array &$form_state) {
     if (!empty($form_state['values']['categories'])) {
-      foreach ($form_state['values']['categories'] as $iid => $selection) {
-        $this->database->delete('aggregator_category_item')
-          ->condition('iid', $iid)
-          ->execute();
-        $insert = $this->database->insert('aggregator_category_item')
-          ->fields(array('iid', 'cid'));
-        $has_values = FALSE;
-        foreach ($selection as $cid) {
-          if ($cid && $iid) {
-            $has_values = TRUE;
-            $insert->values(array(
-              'iid' => $iid,
-              'cid' => $cid,
-            ));
-          }
-        }
-        if ($has_values) {
-          $insert->execute();
-        }
+      foreach ($form_state['values']['categories'] as $iid => $cids) {
+        $this->categoryStorage->updateCategoriesForItem($iid, $cids);
       }
     }
     drupal_set_message($this->t('The categories have been saved.'));