Here's the wrapup, thanks to those who replied: - the haskell zlib package on hackage no longer requires that zlib (the C library) be prebuilt. It includes sources itself and builds and installs them using Cabal. - the haskell zlib package is not used by darcs. It links against libz.a directly. You do need to have libz.a somehow to build darcs. - the darcs link error with "SleepEx" is caused because it uses "foreign import ccall" when it should use "foreign import stdcall". Fixing the decl in src/win32/System/Posix.hs to stdcall fixes this issue. I still think its odd that ghc's "gcc" is not very useable outside of Cabal, but in this case it has no bearing on the zlib package. If you choose to build "libz.a" (the C library) from sources using this gcc it will be hard, but you could also get it from an external source (such as the prebuilt libcurl library package). Tim Newsham http://www.thenewsh.com/~newsham/