diff --git a/src/mess/drivers/c64.c b/src/mess/drivers/c64.c
index bc1ced55e25..e799933a15d 100644
--- a/src/mess/drivers/c64.c
+++ b/src/mess/drivers/c64.c
@@ -1334,8 +1334,8 @@ static MACHINE_CONFIG_START( pal_gs, c64gs_state )
 	MCFG_PLS100_ADD(PLA_TAG)
 	MCFG_MOS6526_ADD(MOS6526_1_TAG, VIC6569_CLOCK, 50, WRITELINE(c64_state, cia1_irq_w))
 	MCFG_MOS6526_SERIAL_CALLBACKS(DEVWRITELINE(PET_USER_PORT_TAG, pet_user_port_device, write_4), DEVWRITELINE(PET_USER_PORT_TAG, pet_user_port_device, write_5))
-	MCFG_MOS6526_PORT_A_CALLBACKS(READ8(c64_state, cia1_pa_r), NULL)
-	MCFG_MOS6526_PORT_B_CALLBACKS(READ8(c64_state, cia1_pb_r), WRITE8(c64_state, cia1_pb_w), NULL)
+	MCFG_MOS6526_PORT_A_CALLBACKS(READ8(c64gs_state, cia1_pa_r), NULL)
+	MCFG_MOS6526_PORT_B_CALLBACKS(READ8(c64gs_state, cia1_pb_r), WRITE8(c64gs_state, cia1_pb_w), NULL)
 	MCFG_MOS6526_ADD(MOS6526_2_TAG, VIC6567_CLOCK, 60, WRITELINE(c64_state, cia2_irq_w))
 	MCFG_MOS6526_SERIAL_CALLBACKS(DEVWRITELINE(PET_USER_PORT_TAG, pet_user_port_device, write_6), DEVWRITELINE(PET_USER_PORT_TAG, pet_user_port_device, write_7))
 	MCFG_MOS6526_PORT_A_CALLBACKS(READ8(c64_state, cia2_pa_r), WRITE8(c64_state, cia2_pa_w))