Malcolm, when you modified AuxTypes.hs you probably added a dependeny on PackedString. However, the directory compiler98 does not contain that file. You should probably add it. Ciao, Olaf When building hat: hmake -hc=ghc -package base -prof -auto-all -d /nfs/myrtle/d23/part1/home/cur/oc/HatWrite/targets/sparc-solaris2/obj/hattrans -I. -I../compiler98 HatTrans MkProg: Can't find module PackedString in user directories . . ../compiler98 Or in installed libraries/packages at /proj/haskell/lib/ghc-6.4.1/imports /proj/haskell/lib/ghc-6.4.1/imports Asked for by: AuxTypes.hs Fix using the -I, -P, or -package flags.