diff --git a/lib/util.js b/lib/util.js
index e4a7660..a4611f0 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -118,7 +118,7 @@ function generatePreviewHead(parsedConfig) {
   for(const key of Object.keys(parsedConfig)) {
     for(const value of parsedConfig[key]) {
       if(key == 'script') {
-        if(value.src.indexOf('ember-cli-live-reload.js') > -1) {
+        if(value.src && value.src.indexOf('ember-cli-live-reload.js') > -1) {
           doc.push(`<script>
             (function() {
               var srcUrl = null;
@@ -137,7 +137,7 @@ function generatePreviewHead(parsedConfig) {
           continue;
         }
         doc.push(`<${key} ${objectToHTMLAttributes(value)}></${key}>`);
-        if(value.src.indexOf('assets/vendor.js') > -1) {
+        if(value.src && value.src.indexOf('assets/vendor.js') > -1) {
           // make sure we push this right after vendor to ensure the application does not bind to the window.
           doc.push('<script>runningTests = true; Ember.testing=true;</script>');
         }