diff --git a/src/mame/drivers/microdec.cpp b/src/mame/drivers/microdec.cpp
index dfb4536a1bd..dd6df214b0e 100644
--- a/src/mame/drivers/microdec.cpp
+++ b/src/mame/drivers/microdec.cpp
@@ -183,7 +183,7 @@ DRIVER_INIT_MEMBER( microdec_state, microdec )
 
 static MACHINE_CONFIG_START( microdec )
 	/* basic machine hardware */
-	MCFG_CPU_ADD("maincpu",Z80, XTAL_4MHz)
+	MCFG_CPU_ADD("maincpu", Z80, XTAL_16MHz / 4)
 	MCFG_CPU_PROGRAM_MAP(microdec_mem)
 	MCFG_CPU_IO_MAP(microdec_io)