diff --git a/examples/timeline/markers/customTimeMarkersEditable.html b/examples/timeline/markers/customTimeMarkersEditable.html
index 11949d2d6e..2424349be4 100644
--- a/examples/timeline/markers/customTimeMarkersEditable.html
+++ b/examples/timeline/markers/customTimeMarkersEditable.html
@@ -30,8 +30,8 @@
   };
   var timeline = new vis.Timeline(container, items, options);
 
-  var id1 = new Date().getTime();
-  var id2 = new Date().getTime();
+  var id1 = 'id1';
+  var id2 = 'id2';
   timeline.addCustomTime(new Date(customDate.getFullYear(), customDate.getMonth(), customDate.getDate() + 2), id1);
   timeline.setCustomTimeMarker("This is editable", id1, true);
   timeline.addCustomTime(new Date(customDate.getFullYear(), customDate.getMonth(), customDate.getDate() + 3), id2);