Ian This getRegister bug is killing my Windows builds too; indeed every 32-bit build is broken, and that is stalling a lot of people, now including me. Could you perhaps revert the patch (around 6 June) that caused this, until it's sorted out? Thanks Simon "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -H32m -O -Werror -Wall -H64m -O0 -package-name ghc-prim-0.3.1.0 -hide-all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim/dist-install/build/autogen -Ilibraries/ghc-prim/dist-install/build -Ilibraries/ghc-prim/dist-install/build/autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist-install/build/autogen/cabal_macros.h -package rts-1.0 -package-name ghc-prim -XHaskell98 -XCPP -XMagicHash -XForeignFunctionInterface -XUnliftedFFITypes -XUnboxedTuples -XEmptyDataDecls -XNoImplicitPrelude -O2 -O -dcore-lint -fno-warn-deprecated-flags -no-user-package-db -rtsopts -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist-install/build -stubdir libraries/ghc-prim/dist-install/build -dynamic-too -c libraries/ghc-prim/dist-install/build/GHC/PrimopWrappers.hs -o libraries/ghc-prim/dist-install/build/GHC/PrimopWrappers.o -dyno libraries/ghc-prim/dist-install/build/GHC/PrimopWrappers.dyn_o ghc-stage1.exe: panic! (the 'impossible' happened) (GHC version 7.7.20130611 for i386-unknown-mingw32): getRegister(x86) I64[Sp] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug bash-3.1$