Hi.. I've found the nice documentation about building ghc on haskell.org/ghc -> documentation. There is one chapter (#1) about C compilers and environments to use: Either MSYS or cywin and gcc of MinGW because gcc of cygwin will link to cygwin1.dll by default which may change and therefore can brake your apps. Googling around I've found that there exists the -mno-cygwin flag which you can use to not include this lib.. So would it might be possible to get a ghc build not using cygwin.dll with just cygwin ? I haven't read anything about that in those docs. Or does this flag simply include cygwin.dll within your apps (statically linked) ? #1 :http://www.haskell.org/ghc/docs/latest/html/building/platforms.html#ghc-cygw... Marc