diff --git a/core/modules/aggregator/tests/modules/aggregator_test/lib/Drupal/aggregator_test/Plugin/aggregator/processor/TestProcessor.php b/core/modules/aggregator/tests/modules/aggregator_test/lib/Drupal/aggregator_test/Plugin/aggregator/processor/TestProcessor.php
index a0ba7f2..1e7dc4f 100644
--- a/core/modules/aggregator/tests/modules/aggregator_test/lib/Drupal/aggregator_test/Plugin/aggregator/processor/TestProcessor.php
+++ b/core/modules/aggregator/tests/modules/aggregator_test/lib/Drupal/aggregator_test/Plugin/aggregator/processor/TestProcessor.php
@@ -67,14 +67,14 @@ public function buildConfigurationForm(array $form, array &$form_state) {
     $processors = $this->configFactory->get('aggregator.settings')->get('processors');
     $info = $this->getPluginDefinition();
 
-    $form['processors'][$this->getPluginId()] = array(
+    $form['processors'][$info['id']] = array(
       '#type' => 'details',
       '#title' => t('Test processor settings'),
       '#description' => $info['description'],
-      '#collapsed' => !in_array($this->getPluginId(), $processors),
+      '#collapsed' => !in_array($info['id'], $processors),
     );
     // Add some dummy settings to verify settingsForm is called.
-    $form['processors'][$this->getPluginId()]['dummy_length'] = array(
+    $form['processors'][$info['id']]['dummy_length'] = array(
       '#title' => t('Dummy length setting'),
       '#type' => 'number',
       '#min' => 1,