I used cabal to install Crypto and it seemed to work fine Here is what I see at the prompt when I try to import the module $ ghci GHCi, version 7.4.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> :m +Crypto <no location info>: Could not find module `Crypto' It is not a module in the current program, or in any known package. Prelude> :m +Crypto.Hash <no location info>: Could not find module `Crypto.Hash' It is not a module in the current program, or in any known package. Prelude> :m +Crypto.Hash.Data <no location info>: Could not find module `Crypto.Data' It is not a module in the current program, or in any known package. Here is my package list. $ ghc-pkg list /var/lib/ghc/package.conf.d Cabal-1.14.0 array-0.4.0.0 base-4.5.0.0 bin-package-db-0.0.0.0 binary-0.5.1.0 bytestring-0.9.2.1 containers-0.4.2.1 deepseq-1.3.0.0 directory-1.1.0.2 extensible-exceptions-0.1.1.4 filepath-1.3.0.0 ghc-7.4.1 ghc-prim-0.2.0.0 haskell2010-1.1.0.1 haskell98-2.0.0.1 hoopl-3.8.7.3 hpc-0.5.1.1 integer-gmp-0.4.0.0 old-locale-1.0.0.4 old-time-1.1.0.0 pretty-1.1.1.0 process-1.1.0.1 rts-1.0 template-haskell-2.7.0.0 time-1.4 unix-2.5.1.0 /home/dlee/.ghc/i386-linux-7.4.1/package.conf.d Crypto-4.2.5.1 HUnit-1.3.0.0 QuickCheck-2.8.1 primitive-0.6.1.0 random-1.1 tf-random-0.5 transformers-0.4.3.0 I'd appreciate tips on how to troubleshoot what's going on. -- Dustin Lee qhfgva=rot13(dustin) ᕕ( ᐛ )ᕗ