I can’t build a profiled HEAD compiler. In validate.mk I put GhcProfiled = YES GhcStage1HcOpts = -DDEBUG GhcStage2HcOpts = -fprof-auto GhcLibHcOpts += -Wwarn GhcLibWays += p But then ‘sh validate –fast’ gives rts/RtsFlags.c: In function ‘read_heap_profiling_flag’: rts/RtsFlags.c:1562:26: error: error: assignment discards ‘const’ qualifier from pointer target type [-Werror] rts/RtsFlags.c:1565:27: error: error: assignment discards ‘const’ qualifier from pointer target type [-Werror] cc1: all warnings being treated as errors `gcc' failed in phase `C Compiler'. (Exit code: 1) Does anyone have ideas for how to fix this? Simon