diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Form/SettingsForm.php b/core/modules/aggregator/lib/Drupal/aggregator/Form/SettingsForm.php
index f69c8be..6abd8d9 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Form/SettingsForm.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Form/SettingsForm.php
@@ -33,7 +33,7 @@ class SettingsForm extends ConfigFormBase {
    *
    * @var \Drupal\Core\Plugin\PluginFormInterface[]
    */
-  protected $configurableInstances = array();
+  protected $configurableInstances;
 
   /**
    * The aggregator plugin definitions.