I had the same problem (among others) while trying to install haskell-elm, incidentally. it might be due to there being both haskell-core/cabal-install 1.18.0.3-8 [installed] extra/cabal-install 1.20.0.1-1 [installed: 1.18.0.3-8] but haskell-core is before extra in my pacman.conf. full list of repos: [core] [haskell-core] [haskell-happstack] [infinality-bundle] [infinality-bundle-fonts] [extra] [community] ----------------------------------------------------------- Here's the issue: $ cabal --version cabal-install version 1.18.0.3 using version 1.18.1.3 of the Cabal library $ sudo aura -A aura aura >>= Determining dependencies... aura >>= AUR Packages: aura aura >>= Continue? [Y/n] y aura >>= Building `aura`... aura >>= Well, building `aura` failed. aura >>= Dumping makepkg output in 3.. 2.. 1.. ==> Making package: aura 1.2.3.4-1 (Sun May 25 14:31:03 PDT 2014) ==> Checking runtime dependencies... ==> Checking buildtime dependencies... ==> Retrieving sources... -> Downloading aura-1.2.3.4.tar.gz... % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 100 99115 100 99115 0 0 66012 0 0:00:01 0:00:01 --:--:-- 29312 ==> Validating source files with md5sums... aura-1.2.3.4.tar.gz ... Passed ==> Extracting sources... -> Extracting aura-1.2.3.4.tar.gz with bsdtar ==> Starting build()... Setup.hs:1:8: Could not find module ‘Distribution.Simple’ Perhaps you haven't installed the "dyn" libraries for package ‘Cabal-1.20.0.0’? Use -v to see a list of the files searched for. ==> ERROR: A failure occurred in build(). Aborting... aura >>= Would you like to continue anyway? [Y/n] n aura >>= Building failed.