diff -u b/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
--- b/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -56,7 +56,7 @@
     $variables['compact'] = system_admin_compact_mode();
     foreach ($variables['content'] as $key => $item) {
       $variables['content'][$key]['link'] = \Drupal::linkGenerator()->generateFromUrl($item['title'], $item['url']);
-      if (!$compact && isset($item['description'])) {
+      if (!$variables['compact'] && isset($item['description'])) {
         $variables['content'][$key]['description'] = Xss::filterAdmin($item['description']);
       }
       else {