Hooking into parse_query too early?

Hi,
I try to alter a query and used the code below in a plugin file.

It works without problems if I add it to another plugin I downloaded but I want to keep my modifications separate.

I did some research and one guy said to someone with a similar problem that the hook is called in my plugin before even parse_query was executed and that’s why it doesn’t work.

Any idea how I can make this work?

<?php
/*
Plugin Name: Tweak
Plugin URI: http://wordpress.org/extend/plugins/hello-dolly/
Description: Little tweak
Author: Mmmkay
Version: 0.1
Author URI: http://nonono.com
*/

function parse_query( $wp_query ) {

		$wp_query->set( 'post_type', 'post' );

	}

add_action( 'parse_query', array( &$this, 'parse_query' ) );