C# - How To Compress .ashx Content

In my web application I use an ashx file to write a file to the browser. I've noticed that there's no compression over the .ashx file, but only over my .aspx files.

Is it possible to compress .ashx? And if it is possible, how?

Currently I use global.asax to handle the compression:

<%@ Application Language="C#" %>
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.IO.Compression" %>
<script runat="server">
void Application_PreRequestHandlerExecute(object sender, EventArgs e)
{
HttpApplication app = sender as HttpApplication;.......

As you can see only files which inherit from 'Page' are compressed, and my ashx file is not of type Page. So I added a condition and now it works just fine:

if (!(app.Context.CurrentHandler is Page ||
app.Context.CurrentHandler.GetType().Name == "SyncSessionlessHandler" ||
app.Context.CurrentHandler is ViewMht // This is the type I had to add
) ||
app.Request["HTTP_X_MICROSOFTAJAX"] != null)
return;