diff --git a/core/modules/block/custom_block/custom_block.pages.inc b/core/modules/block/custom_block/custom_block.pages.inc
index b9fa88f..a0dc773 100644
--- a/core/modules/block/custom_block/custom_block.pages.inc
+++ b/core/modules/block/custom_block/custom_block.pages.inc
@@ -10,32 +10,25 @@
 use Symfony\Component\HttpFoundation\RedirectResponse;
 
 /**
- * Returns HTML for a list of available custom block types for block creation.
+ * Prepares variables for a custom block type creation list templates.
  *
- * @param $variables
+ * Default template: custom-block-add-list.html.twig.
+ *
+ * @param array $variables
  *   An associative array containing:
  *   - content: An array of block types.
  *
  * @see custom_block_add_page()
- *
- * @ingroup themeable
  */
-function theme_custom_block_add_list($variables) {
-  $content = $variables['content'];
-  $output = '';
-
-  if ($content) {
-    $output = '<dl class="node-type-list">';
-    foreach ($content as $type) {
-      $output .= '<dt>' . l($type->label(), 'block/add/' . $type->id()) . '</dt>';
-      $output .= '<dd>' . filter_xss_admin($type->description) . '</dd>';
-    }
-    $output .= '</dl>';
+function template_preprocess_custom_block_add_list(&$variables) {
+  $variables['types'] = array();
+  foreach ($variables['content'] as $type) {
+    $variables['types'][$type->id] = array();
+    $variables['types'][$type->id]['link'] = l($type->label(), 'block/add/' . $type->id());
+    $variables['types'][$type->id]['description'] = filter_xss_admin($type->description);
   }
-  return $output;
 }
 
-
 /**
  * Page callback: Presents the custom block creation form.
  *
@@ -100,10 +93,6 @@ function custom_block_delete_form($form, &$form_state, CustomBlock $block) {
   );
 
   $instances = $block->getInstances();
-  $form['instances'] = array(
-    '#type' => 'value',
-    '#value' => $instances,
-  );
 
   $form['message'] = array(
     '#type' => 'markup',
diff --git a/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php b/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php
index f62dd0d..e44aa75 100644
--- a/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php
+++ b/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php
@@ -125,6 +125,9 @@ public function testBlockDelete() {
 
     $block = custom_block_load(1);
 
+    // Test getInstances method.
+    $this->assertEqual(1, count($block->getInstances()));
+
     // Navigate to home page.
     $this->drupalGet('');
     $this->assertText($body);