diff --git a/core/modules/system/lib/Drupal/system/DateFormatFormControllerBase.php b/core/modules/system/lib/Drupal/system/DateFormatFormControllerBase.php
index 070444f..75909c8 100644
--- a/core/modules/system/lib/Drupal/system/DateFormatFormControllerBase.php
+++ b/core/modules/system/lib/Drupal/system/DateFormatFormControllerBase.php
@@ -152,7 +152,7 @@ public function form(array $form, array &$form_state) {
         '#type' => 'select',
         '#options' => $options,
         '#multiple' => TRUE,
-        '#default_value' => '',
+        '#default_value' => $this->entity->getLocales(),
       );
     }