diff --git a/bootstrap-tree/js/bootstrap-tree.js b/bootstrap-tree/js/bootstrap-tree.js
index 237138a..f64cf27 100644
--- a/bootstrap-tree/js/bootstrap-tree.js
+++ b/bootstrap-tree/js/bootstrap-tree.js
@@ -156,7 +156,7 @@
           
           var branch = $("<ul>").addClass("branch")
           
-          attributes.class = "tree-toggle closed"
+          attributes["class"] = "tree-toggle closed"
           attributes["data-toggle"] = "branch"
             
         }
@@ -457,4 +457,4 @@
     
   })
 
-}(window.jQuery);
\ No newline at end of file
+}(window.jQuery);