Install specific version of X11 for xmonad?

I wanted to compile xmonad from source, so I checked out the code and ran the first command from the README. $ runhaskell Setup.lhs configure --user --prefix=$HOME Configuring xmonad-0.12... Setup.lhs: At least the following dependencies are missing: X11 >=1.5 && <1.7 Apparently haskell wants a specific version of X11. This kind of scares me, as whenever I touch video-specific items like Xorg or video drivers, I tend to completely bork my system. 1. Is it safe to install a specific newer version of X11? 2. How would I do so? Is it possible to use apt-get?