This could be an artifact of the -j64 (BTW, has anyone else noticed the makefiles can only keep 5 or 6 cpus busy at a time much of the time, and often less?). gcc -O -ffunction-sections -c Text/Regex/Posix_hsc.c -o Text/Regex/Posix_hsc.o Text/ParserCombinators/Parsec/Pos.hs:15: failed to load interface for `Prelude': Bad interface file: /mnt/h/tmp/ghc5-5.04/build-stage1/libraries/base/Prelude.hi does not exist Action: openFileEx Reason: No such file or directory File: /mnt/h/tmp/ghc5-5.04/build-stage1/libraries/base/Prelude.hi make[4]: *** [Text/ParserCombinators/Parsec/Pos.o] Error 1 make[4]: *** Waiting for unfinished jobs.... GHC/PrimopWrappers.hs:2: failed to load interface for `GHC.Base': Bad interface file: /mnt/h/tmp/ghc5-5.04/build-stage1/libraries/base/GHC/Base.hi does not exist Action: openFileEx Reason: No such file or directory File: /mnt/h/tmp/ghc5-5.04/build-stage1/libraries/base/GHC/Base.hi GHC/PrimopWrappers.hs:2: Failed to find interface decl for `GHC.Base.eqString' from module `GHC.Base' GHC/PrimopWrappers.hs:2: Failed to find interface decl for `GHC.Base.unpackCStringUtf8#' from module `GHC.Base' GHC/PrimopWrappers.hs:2: Failed to find interface decl for `GHC.Base.unpackFoldrCString#' from module `GHC.Base' GHC/PrimopWrappers.hs:2: Failed to find interface decl for `GHC.Base.unpackCString#' from module `GHC.Base' make[4]: *** [GHC/PrimopWrappers.o] Error 1 make[3]: *** [all] Error 1 make[3]: Leaving directory `/mnt/h/tmp/ghc5-5.04/build-stage1/libraries' make[2]: *** [all] Error 1 make[2]: Leaving directory `/mnt/h/tmp/ghc5-5.04/build-stage1' make[1]: *** [build-stage1] Error 2 make[1]: Leaving directory `/mnt/h/tmp/ghc5-5.04' make: *** [stamps/build-stamp] Error 2 debuild: fatal error at line 456: dpkg-buildpackage failed!