I was able to build encoding-0.6.2. My steps: (0. Update package list with 'cabal update') 1. Unpack package with 'cabal unpack encoding' 2. Edit encoding.cabal. We need to add HaXml as dependency. It should be added to 'Build-Depends' field. I've added below "HaXml == 1.20.2" because 1.20.2. is the latest version available at the time of writing. Library if flag(splitBase) if flag(newGHC) Build-Depends: bytestring, base >= 3 && < 5, binary, mtl, containers, extensible-exceptions, array, template-haskell, regex-compat, ghc-prim, ghc >= 6.10, HaXml == 1.20.2 else Build-Depends: bytestring, base >= 3 && < 5, binary, mtl, containers, extensible-exceptions, array, template-haskell, regex-compat, ghc < 6.10, HaXml == 1.20.2 else Build-Depends: base < 3, binary, extensible-exceptions, template-haskell 3. Instal with "cabal install" run in the directory next to encoding.cabal. It looks like package maintainer forgot to specify this dependency. Best regards Krzysztof Skrzętnicki