diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Form/SettingsForm.php b/core/modules/aggregator/lib/Drupal/aggregator/Form/SettingsForm.php
index 54dc385..1e9e906 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Form/SettingsForm.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Form/SettingsForm.php
@@ -36,6 +36,13 @@ class SettingsForm extends SystemConfigFormBase {
   );
 
   /**
+   * The instanciated plugin instances.
+   *
+   * @var array
+   */
+  protected $instances = array();
+
+  /**
    * Constructs a \Drupal\aggregator\SettingsForm object.
    *
    * @param \Drupal\Core\Config\ConfigFactory $config_factory
@@ -82,7 +89,7 @@ public function getFormID() {
   }
 
   /**
-   * Implements \Drupal\Core\Form\FormInterface::buildForm().
+   * {@inheritdoc}
    */
   public function buildForm(array $form, array &$form_state) {
     $config = $this->configFactory->get('aggregator.settings');
@@ -140,9 +147,10 @@ public function buildForm(array $form, array &$form_state) {
     foreach (array('fetcher', 'parser') as $type) {
       $active = $config->get($type);
       if (array_key_exists($active, $this->definitions[$type])) {
-        $form = $this->managers[$type]
-          ->createInstance($active)
-          ->settingsForm($form, $form_state);
+        $instance = $this->managers[$type]->createInstance($active);
+        $form = $instance->settingsForm($form, $form_state);
+        // Store the instance for validate and submit handlers.
+        $this->instances[] = $instance;
       }
     }
 
@@ -151,33 +159,36 @@ public function buildForm(array $form, array &$form_state) {
     // Call settingsForm() for each active processor.
     foreach ($this->definitions['processor'] as $id => $definition) {
       if (in_array($id, $config->get('processors'))) {
-        $form = $this->managers['processor']->createInstance($id)->settingsForm($form, $form_state);
+        $instance = $this->managers['processor']->createInstance($id);
+        $form = $instance->settingsForm($form, $form_state);
+        // Store the instance for validate and submit handlers.
+        $this->instances[] = $instance;
       }
     }
     return parent::buildForm($form, $form_state);
   }
 
   /**
-   * Implements \Drupal\Core\Form\FormInterface::submitForm().
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, array &$form_state) {
+    parent::validateForm($form, $form_state);
+    // Let active plugins validate their settings.
+    foreach ($this->instances as $instance) {
+      $instance->settingsValidate($form, $form_state);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
    */
   public function submitForm(array &$form, array &$form_state) {
     parent::submitForm($form, $form_state);
     $config = $this->configFactory->get('aggregator.settings');
 
-    // Let active fetcher and parser save their settings.
-    foreach (array('fetcher', 'parser') as $type) {
-      $active = $config->get($type);
-      if (array_key_exists($active, $this->definitions[$type])) {
-        $this->managers[$type]
-          ->createInstance($active)
-          ->settingsSubmit($form, $form_state);
-      }
-    }
-    // Let active processors save their settings.
-    foreach ($this->definitions['processor'] as $id => $definition) {
-      if (in_array($id, $config->get('processors'))) {
-        $this->managers['processor']->createInstance($id)->settingsSubmit($form, $form_state);
-      }
+    // Let active plugins save their settings.
+    foreach ($this->instances as $instance) {
+      $instance->settingsSubmit($form, $form_state);
     }
 
     $config->set('items.allowed_html', $form_state['values']['aggregator_allowed_html_tags']);