Contact Form 7 Input Fields Values as PHP Get-Viarables

Hello,

I am using the Contact form 7 plugin, and what I would like to do is have the default text for a input field, be generated via query string.

So I would think that the code would look something like this:
[text* postID “<?php echo $_GET[‘postid’];?>”]

and the url would obviously end in ?postid=3

But that causes the text fied on the page to crash. Any ideas how to accomplish this?