diff --git a/menu_block.module b/menu_block.module
index 83cf0c9..1e7345b 100644
--- a/menu_block.module
+++ b/menu_block.module
@@ -301,8 +301,9 @@ function menu_tree_build($config) {

   // Get the default block name.
   $menu_names = menu_block_get_all_menus();
-  menu_block_set_title(t($menu_names[$config['menu_name']]));
-
+  if (array_key_exists($config['menu_name'], $menu_names)) {
+    menu_block_set_title(t($menu_names[$config['menu_name']]));
+  }
   if ($config['expanded'] || $config['parent_mlid']) {
     // Get the full, un-pruned tree.
     $tree = menu_tree_all_data($config['menu_name']);
@@ -410,7 +411,9 @@ function menu_block_get_title($render_title_as_link = TRUE) {
   }
   // The tree's title is a menu item.
   else {
-    $title = array('#markup' => check_plain($menu_item['title']));
+    if (array_key_exists('title', $menu_item)) {
+      $title = array('#markup' => check_plain($menu_item['title']));
+    }
   }
   return $title;
 }