diff --git a/lib/timeline/Core.js b/lib/timeline/Core.js
index fa843ceff..dadb1d4bb 100644
--- a/lib/timeline/Core.js
+++ b/lib/timeline/Core.js
@@ -299,7 +299,7 @@ Core.prototype._create = function (container) {
     }
 
     // make sure your target is a vis element
-    if (!event.target.className.indexOf("vis") > -1) return;
+    if (!(event.target.className.indexOf("vis") > -1)) return;
 
     // make sure only one item is added every time you're over the timeline
     if (itemAddedToTimeline) return;