diff --git a/core/includes/menu.inc b/core/includes/menu.inc
index 66d1e2a..1ec5289 100644
--- a/core/includes/menu.inc
+++ b/core/includes/menu.inc
@@ -3388,9 +3388,15 @@ function _menu_site_is_offline($check_only = FALSE) {
   if (config('system.maintenance')->get('enabled')) {
     if (user_access('access site in maintenance mode')) {
       // Ensure that the maintenance mode message is displayed only once
-      // (allowing for page redirects) and specifically suppress its display on
-      // the maintenance mode settings page.
-      if (!$check_only && current_path() != 'admin/config/development/maintenance') {
+      // (allowing for page redirects).
+      if (!$check_only) {
+        // Specifically suppress its display on the maintenance mode settings
+        // page or when a Toolbar subtree is loaded.
+        if (current_path() == 'admin/config/development/maintenance' ||
+          substr(current_path(), 0, 17) == 'toolbar/subtrees/') {
+          return FALSE;
+        }
+
         if (user_access('administer site configuration')) {
           drupal_set_message(t('Operating in maintenance mode. <a href="@url">Go online.</a>', array('@url' => url('admin/config/development/maintenance'))), 'status', FALSE);
         }