(i hope this is not a repost - sent it to haskell-cafe-bounces the first time) new thread because i have the details i should have provided in the first place. development system is centos 6.6 but i suspect something's broken because... i built and installed gmp-4.3.2 only to find that it's being build as a 32-bit library and will only build as 32-bits. which is really weird, because 64-bit system: 2.6.32-504.3.3.el6.x86_64 #1 SMP Wed Dec 17 01:55:02 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux however- no problem- i'll simply download the 32-bit version of the ghc binary, which was built on centos no less, and install that instead of the 64-bit version. so i do that, point configure at my gmp thusly ./configure --prefix=/home/denheyer/local --with-gmp-includes=/home/denheyer/local/include --with-gmp-libraries=/home/denheyer/local/lib and get this checking for path to top of build tree... utils/ghc-pwd/dist-install/build/tmp/ghc-pwd: error while loading shared libraries: libgmp.so.3: cannot open shared object file: No such file or directory configure: error: cannot determine current directory ok- i haven't seen it do that before, but it's probably because i'm pointing it away from it's internal libgmp. that's fine, i'll set LD_LIBRARY_PATH. I do that and make install starts to work. yay! and then i get THIS ghc-cabal: Bad interface file: dist-install/build/GHC/CString.hi magic number mismatch: old/corrupt interface file? (wanted 33214052, got 129742) somebody really hates me. so originally i had downloaded the xz file, and even though i figure it's pretty much impossible that the archive was actually corrupted, i decide to download the bzip version just in case. yeah- not surprisingly, the build still breaks. any ideas ?? Thanks, Brian