diff --git a/test/TimelineItemSet.test.js b/test/TimelineItemSet.test.js
index 8892c49e..50265d0e 100644
--- a/test/TimelineItemSet.test.js
+++ b/test/TimelineItemSet.test.js
@@ -1,4 +1,5 @@
 var assert = require('assert');
+var vis = require('../dist/vis');
 
 describe('Timeline ItemSet', function () {
   before(function () {