diff --git a/src/mame/drivers/timeplt.cpp b/src/mame/drivers/timeplt.cpp
index ab717e34348..1131bb51008 100644
--- a/src/mame/drivers/timeplt.cpp
+++ b/src/mame/drivers/timeplt.cpp
@@ -495,7 +495,7 @@ MACHINE_CONFIG_DERIVED(timeplt_state::chkun, bikkuric)
 
 	/* sound hardware */
 	MCFG_SOUND_MODIFY("timeplt_audio:ay2")
-	MCFG_AY8910_PORT_A_WRITE_CB(WRITE8(timeplt_state, chkun_sound_w))
+	MCFG_AY8910_PORT_A_WRITE_CB(DEVWRITE8("^", timeplt_state, chkun_sound_w))
 
 	MCFG_TC8830F_ADD("tc8830f", XTAL_512kHz)
 	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "timeplt_audio:mono", 0.10)