diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index c55289c..b102a6e 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -1598,7 +1598,7 @@ function system_performance_settings($form, &$form_state) {
   $config = config('system.performance');
 
   $form['clear_cache'] = array(
-    '#type' => 'fieldset',
+    '#type' => 'details',
     '#title' => t('Clear cache'),
   );
 
@@ -1609,7 +1609,7 @@ function system_performance_settings($form, &$form_state) {
   );
 
   $form['caching'] = array(
-    '#type' => 'fieldset',
+    '#type' => 'details',
     '#title' => t('Caching'),
   );
 
@@ -1639,7 +1639,7 @@ function system_performance_settings($form, &$form_state) {
   }
 
   $form['bandwidth_optimization'] = array(
-    '#type' => 'fieldset',
+    '#type' => 'details',
     '#title' => t('Bandwidth optimization'),
     '#description' => t('External resources can be optimized automatically, which can reduce both the size and number of requests made to your website.') . $disabled_message,
   );