带有问号的Apache mod_rewrite

I have a PHP-based web app that I'm trying to apply Apache's mod_rewrite to.

Original URLs are of the form:

http://webseite.de/search/What%3F.html

And I'd like to transform these into:

http://webseite.de/index.php?mod=search&mod2=What?

This url already works:

http://webseite.de/search/What.html

My .htaccess file:

RewriteEngine on 
Options +FollowSymlinks
RewriteRule ^([^/]+).html$ index.php?mod=$1
RewriteRule ^(.*)/(.*).html$ index.php?mod=$1&mod2=$2 [NE,B]