diff --git a/core/lib/Drupal/Core/Render/Element/Checkboxes.php b/core/lib/Drupal/Core/Render/Element/Checkboxes.php
index 35611fd3b9..0a343d87e7 100644
--- a/core/lib/Drupal/Core/Render/Element/Checkboxes.php
+++ b/core/lib/Drupal/Core/Render/Element/Checkboxes.php
@@ -78,7 +78,7 @@ public static function processCheckboxes(&$element, FormStateInterface $form_sta
           '#type' => 'checkbox',
           '#title' => $choice,
           '#return_value' => $key,
-          '#default_value' => isset($value[$key]) ? $key : NULL,
+          '#default_value' => isset($value[$key]) || (is_array($element['#default_value']) && in_array($key, $element['#default_value'])) ? $key : NULL,
           '#attributes' => $element['#attributes'],
           '#ajax' => isset($element['#ajax']) ? $element['#ajax'] : NULL,
           // Errors should only be shown on the parent checkboxes element.