diff --git a/src/mame/drivers/m92.c b/src/mame/drivers/m92.c
index 30a47134870..3be293e76de 100644
--- a/src/mame/drivers/m92.c
+++ b/src/mame/drivers/m92.c
@@ -382,7 +382,7 @@ static ADDRESS_MAP_START( lethalth_map, ADDRESS_SPACE_PROGRAM, 16 )
 	AM_RANGE(0xf8800, 0xf8fff) AM_READWRITE(m92_paletteram_r, m92_paletteram_w)
 	AM_RANGE(0xf9000, 0xf900f) AM_WRITE(m92_spritecontrol_w) AM_BASE(&m92_spritecontrol)
 	AM_RANGE(0xf9800, 0xf9801) AM_WRITE(m92_videocontrol_w)
-	AM_RANGE(0xffff0, 0xfffff) AM_ROM
+	AM_RANGE(0xffff0, 0xfffff) AM_ROM AM_REGION("maincpu", 0x7fff0)
 ADDRESS_MAP_END
 
 static ADDRESS_MAP_START( m92_map, ADDRESS_SPACE_PROGRAM, 16 )