diff --git a/js/h5p-x-api.js b/js/h5p-x-api.js
index 9fc6758..6becdad 100644
--- a/js/h5p-x-api.js
+++ b/js/h5p-x-api.js
@@ -95,7 +95,8 @@ H5P.EventDispatcher.prototype.triggerXAPIScored = function (score, maxScore, ver
 H5P.EventDispatcher.prototype.setActivityStarted = function() {
   if (this.activityStartTime === undefined) {
     // Don't trigger xAPI events in the editor
-    if (H5PIntegration.contents['cid-' + this.contentId] !== undefined) {
+    if (H5PIntegration.contents !== undefined &&
+        H5PIntegration.contents['cid-' + this.contentId] !== undefined) {
       this.triggerXAPI('attempted');
     }
     this.activityStartTime = Date.now();
@@ -114,4 +115,4 @@ H5P.xAPICompletedListener = function (event) {
     var contentId = event.getVerifiedStatementValue(['object', 'definition', 'extensions', 'http://h5p.org/x-api/h5p-local-content-id']);
     H5P.setFinished(contentId, score, maxScore);
   }
-};
\ No newline at end of file
+};