diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 721bcf8..083f78d 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -175,6 +175,7 @@ function system_theme() {
     ),
     'confirm_form' => array(
       'render element' => 'form',
+      'template' => 'confirm-form',
     ),
     'system_modules_details' => array(
       'render element' => 'form',
@@ -1925,22 +1926,6 @@ function system_run_automated_cron() {
 }
 
 /**
- * Returns HTML for a confirmation form.
- *
- * By default this does not alter the appearance of a form at all,
- * but is provided as a convenience for themers.
- *
- * @param $variables
- *   An associative array containing:
- *   - form: A render element representing the form.
- *
- * @ingroup themeable
- */
-function theme_confirm_form($variables) {
-  return drupal_render_children($variables['form']);
-}
-
-/**
  * Returns HTML for a system settings form.
  *
  * By default this does not alter the appearance of a form at all,
diff --git a/core/modules/system/templates/confirm-form.html.twig b/core/modules/system/templates/confirm-form.html.twig
new file mode 100644
index 0000000..d714917
--- /dev/null
+++ b/core/modules/system/templates/confirm-form.html.twig
@@ -0,0 +1,15 @@
+{#
+/**
+ * @file
+ * Default theme implementation for confirm form.
+ *
+ * By default this does not alter the appearance of a form at all,
+ * but is provided as a convenience for themers.
+ *
+ * Available variables:
+ * - form: The confirm form.
+ *
+ * @ingroup themeable
+ */
+#}
+{{ form }}