[aur-general] Filenames with "_" in it

I have one package[1] in AUR which has a "_" in the original file name. When I put source=(http://downloads.sourceforge.net/bibcursed/$pkgname_$pkgver.tgz) in the PKGBUILD, it won't work. When I put an \ before the _ it works but on the AUR page this \ will also show up and break the link to the original file. Thomas