Comment #5 on issue 507 by d...@krylov.ws: Pattern match failure in do expression at XMonad/Prompt.hs:601:3-14 http://code.google.com/p/xmonad/issues/detail?id=507 I remove 'decodeString', but it does not fix problem: keyPressHandle :: KeyMask -> KeyStroke -> XP () keyPressHandle m (ks,str) = do km <- gets (promptKeymap . config) kmask <- cleanMask m -- mask is defined in ghc7 case M.lookup (kmask,ks) km of Just action -> action >> updateWindows Nothing -> case str of "" -> eventLoop handle _ -> when (kmask .&. controlMask == 0) $ do insertString (decodeString str) updateWindows completed <- tryAutoComplete when completed $ setSuccess True >> setDone True to keyPressHandle :: KeyMask -> KeyStroke -> XP () keyPressHandle m (ks,str) = do km <- gets (promptKeymap . config) kmask <- cleanMask m -- mask is defined in ghc7 case M.lookup (kmask,ks) km of Just action -> action >> updateWindows Nothing -> case str of "" -> eventLoop handle _ -> when (kmask .&. controlMask == 0) $ do insertString str updateWindows completed <- tryAutoComplete when completed $ setSuccess True >> setDone True Please, fix this bug!!