Hi again... What is the cause of these errors? Without -t it compiles fine, as does a tiny test program with -t. I can make the source available if needed, but it is large and I suspect I'm doing something silly. HFLAGS="+RTS -K11048576 -RTS -nkpat" hmake -t -nhc98 main nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o Tokens.z.o Tokens.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o PC_base.z.o PC_base.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o PC.z.o PC.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o Parser.z.o Parser.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o Mangle.z.o Mangle.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o Offside.z.o Offside.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o Scanner.z.o Scanner.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o Args.z.o Args.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -c -o main.z.o main.lhs nhc98 -t +RTS -K11048576 -RTS -nkpat -o main PC_base.z.o PC.z.o Parser.z.o Mangle.z.o Offside.z.o Scanner.z.o Tokens.z.o Args.z.o main.z.o PC_base.z.o(.data+0x8): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x3c): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0xa0): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0xd0): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x124): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x158): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x1b0): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x1e4): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x240): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x274): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x2c8): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x304): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x390): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x3c4): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x424): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x458): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x4f0): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x524): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x5b4): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x5e4): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x618): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x64c): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x688): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x6bc): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x75c): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x788): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x7b4): undefined reference to `TMSUB_PC_95base' PC_base.z.o(.data+0x7e0): undefined reference to `TM_PC_95base' PC_base.z.o(.data+0x814): undefined reference to `TMSUB_PC_95base' collect2: ld returned 1 exit status Thanks Ian