En /etc/apt/sources.list añadimos los fuentes:deb https://mirrordirector.raspbian.org/raspbian/ wheezy main contrib non-free rpi deb-src https://mirrordirector.raspbian.org/raspbian/ wheezy main contrib non-free rpi
Ejecutamos:sudo apt-get update `sudo apt-get build-dep unrar-nonfree sudo apt-get source -b unrar-nonfree`
Fuente.