Hello list, I must be doing something stupid, but what? ghc --version The Glorious Glasgow Haskell Compilation System, version 7.2.1 ghc -E -optP-dM -cpp Main.hs (per http://www.haskell.org/ghc/docs/latest/html/users_guide/options-phases.html) {-# LINE 1 "Main.hs" #-} #define mingw32_HOST_OS 1 #define i386_BUILD_ARCH 1 #define __GLASGOW_HASKELL__ 702 #define __STDC_HOSTED__ 1 #define i386_HOST_ARCH 1 #define mingw32_BUILD_OS 1 I'm on Windows so everything else is correct except the line that tells me I'm using 7.0.2. Unfortunately I have code that works under 7.0.3 and breaks under 7.2.1 (and the 7.2.1 code breaks under 7.0.3, of course) so I don't see anything other option than conditional compilation. What am I doing wrong? Thanks! -- JP Moresmau http://jpmoresmau.blogspot.com/