diff --git a/src/mame/drivers/namcos23.c b/src/mame/drivers/namcos23.c
index c0ba77fc299..77252a46297 100644
--- a/src/mame/drivers/namcos23.c
+++ b/src/mame/drivers/namcos23.c
@@ -3020,7 +3020,8 @@ MACHINE_DRIVER_END
 static MACHINE_DRIVER_START( ss23e2 )
 	MDRV_IMPORT_FROM( ss23 )
 
-	MDRV_CPU_REPLACE("maincpu", R4650BE, S23_BUSCLOCK*6)
+	MDRV_CPU_MODIFY("maincpu")
+	MDRV_CPU_CLOCK(S23_BUSCLOCK*6)
 
 	MDRV_CPU_MODIFY("audiocpu")
 	MDRV_CPU_IO_MAP( s23h8iomap )
@@ -3033,7 +3034,8 @@ MACHINE_DRIVER_END
 static MACHINE_DRIVER_START( gmen )
 	MDRV_IMPORT_FROM( s23 )
 
-	MDRV_CPU_REPLACE("maincpu", R4650BE, S23_BUSCLOCK*5)
+	MDRV_CPU_MODIFY("maincpu")
+	MDRV_CPU_CLOCK(S23_BUSCLOCK*5)
 	MDRV_CPU_PROGRAM_MAP(gmen_mips_map)
 
 	MDRV_CPU_ADD("gmen", SH2, 28700000)