Emberjs IE8 Object expected error

I'm testing my app and while it works in Chrome, FF and Safari, it doesn't load in IE8. I see a blank screen and developer tools reports an error at the very beginning of the js file. The error I get is

Object expected at certilogo-f7ce...js at line 6 character 1

First 6 lines of js file are:

"use strict";
/* jshint ignore:start */

/* jshint ignore:end */

define('certilogo/adapters/application', ['exports', 'ember-data', 'certilogo/config/environment'], function (exports, DS, ENV) {

6th line is the one starting with define(....).

I'm using emberjs 1.13.9 and ember-data version 1.13.11 As per the docs emberjs version 1.13.x should support IE8. What's causing the error and what can I do to solve?

Thanks.