Parse error including vendor/autoload.php

Hey all,

Have a project in CI 2.2.1 and have installed composer. I'm working on setting up the Mixpanel PHP library (https://github.com/mixpanel/mixpanel-php), and got the composer.json file done, ran my update, and so on.

When I require the vendor/autoload.php, I get this error and the screen goes completely blank:
PHP Parse error:  syntax error, unexpected ';' on line 241

At the bottom of my main index.php file, I've added this line which is causing it (line 241):
require 'vendor/autoload.php';

Which is straight out of a Phil Sturgeon article on composer & CI.

Anyone have any ideas on how I can resolve this? Any help is appreciated!

Thanks.