A while ago I wrote a post to this list about the problems that arose when I disabled numlock with xmodmap -e "clear mod2": http://www.haskell.org/pipermail/xmonad/2013-February/013493.html I ended up "fixing" the problem in the legacy application, so I didn't have to muck about with xmodmap. Or so I thought. Today it reared its ugly head again, once and for all telling me that I seriously need to _completely_ disable the numlock key. My first step was to upgrade xmonad to 0.11 and then I tried xmodmap -e "clear mod2" again and of course it still didn't work: My mod key was now non-functional again. /sigh Next step was to dig out the original suggestion from Adam: handleEventHook = ( \e -> case e of MappingNotifyEvent {} -> return (All False) _ -> mempty) I added the above to my xmonad.hs file and then it failed with this: Not in scope: data constructor `All' Not in scope: `mempty' I suspect I need to import something, but what? Here's my xmonad.hs file: https://gist.github.com/ThomasLocke/5196294 Am I missing some crucial parts? :o) Thomas Løcke ps. I found xmonad at github: https://github.com/xmonad/xmonad is this an official repository?