[[!comment format=mdwn username="joey" subject="""comment 1""" date="2017-12-28T17:01:21Z" content=""" The zip file pointed to by the stack.yaml file contains a patched version of threepenny-gui 0.8.0.0, the same as the cabal file requires. Downgrading the dependency won't work, thus your build problems. All I can tell you is it's built successfully with stack every time I've tried to build it, and stack pins all package versions to ensure a reproducible build. It may be that you're using too old a version of stack or something like that; I've used stack 1.1.2. """]]