CSRF giving problem with ajax

I use CSFR protection on my site which is massively Ajaxified. I use a jquery plugin (https://github.com/carhartl/jquery-cookie) that makes handling cookies simple:
<script>
var csrf_token = $.cookie('csrf_token');
</script>

Then whenever I'm POSTing data with Ajax, I just need to include the csrf_token in the data object that's sent to the CI server.

Works really well.