Apache rewrite rule with parameters?

I have the following URL:

http://domain.com/index.php?m=feedback&cSubject=My Subject

I want to have a rewrite rule so that the following:

http://domain.com/feedback?Subject=My Subject

maps to the previous url. Heres my rule at the moment:

RewriteRule ^feedback?Subject=(.*)$ index.php?m=feedback&cSubject=$1

Doesn't seem to be working tho! Any ideas?