JS aggregation doesn't work when a proxy is in place

We have a proxy in front of our Drupal installation and this proxy is configured in Drupal as default proxy for every request.

Now what we found is that omega does some aggregation by it self and tries to access this aggregated file over a request.
So omega makes a request to it self to get this file but is not using the proxy for this request.

Were should I implement/change this?