I just did a rebase to MAME 166 and SUBTARGET seems to faint on me

$ make SUBTARGET=hk68v10 DRIVERS=src/mame/drivers/hk68v10.c REGENIE=1 DEBUG=1 -j9
make: *** No rule to make target `scripts/target/mame/hk68v10.lua', needed by `build/projects/sdl/mamehk68v10/gmake-linux/Makefile'. Stop.

This worked in MAME 165, has the syntax changed?

The usual 'make SUBTARGET=mess -j9' works though but takes for ever to complete after a clean.