Hi Richard, > Configuring cabal-test-quickcheck-0.1.2... > Setup: At least the following dependencies are missing: > Cabal ==1.20.* that error is fixed in revision [1]. Thanks for the report! Best regards, Peter [1] https://github.com/NixOS/nixpkgs/commit/7fa32aecd183f4fcede821a2b0c60a925c0e2ef5.