diff --git a/src/emu/bus/a2bus/a2ssc.c b/src/emu/bus/a2bus/a2ssc.c
index 5b12b98cb31..c56df3aadb1 100644
--- a/src/emu/bus/a2bus/a2ssc.c
+++ b/src/emu/bus/a2bus/a2ssc.c
@@ -28,16 +28,11 @@ const device_type A2BUS_SSC = &device_creator<a2bus_ssc_device>;
 #define SSC_ACIA_TAG    "ssc_acia"
 #define SSC_RS232_TAG   "ssc_rs232"
 
-static SLOT_INTERFACE_START( rs232_devices )
-	SLOT_INTERFACE("serial_terminal", SERIAL_TERMINAL)
-	SLOT_INTERFACE("null_modem", NULL_MODEM)
-SLOT_INTERFACE_END
-
 MACHINE_CONFIG_FRAGMENT( ssc )
 	MCFG_MOS6551_ADD(SSC_ACIA_TAG, XTAL_1_8432MHz, WRITELINE(a2bus_ssc_device, acia_irq_w))
 	MCFG_MOS6551_RXD_TXD_CALLBACKS(NULL, DEVWRITELINE(SSC_RS232_TAG, rs232_port_device, tx))
 
-	MCFG_RS232_PORT_ADD(SSC_RS232_TAG, rs232_devices, NULL)
+	MCFG_RS232_PORT_ADD(SSC_RS232_TAG, default_rs232_devices, NULL)
 	MCFG_SERIAL_OUT_RX_HANDLER(DEVWRITELINE(SSC_ACIA_TAG, mos6551_device, rxd_w))
 	MCFG_RS232_OUT_DCD_HANDLER(DEVWRITELINE(SSC_ACIA_TAG, mos6551_device, dcd_w))
 	MCFG_RS232_OUT_DSR_HANDLER(DEVWRITELINE(SSC_ACIA_TAG, mos6551_device, dsr_w))
diff --git a/src/mess/drivers/amstr_pc.c b/src/mess/drivers/amstr_pc.c
index 5480c3896e6..d70d403e950 100644
--- a/src/mess/drivers/amstr_pc.c
+++ b/src/mess/drivers/amstr_pc.c
@@ -224,7 +224,7 @@ static SLOT_INTERFACE_START( ibmpc_floppies )
 	SLOT_INTERFACE( "525dd", FLOPPY_525_DD )
 SLOT_INTERFACE_END
 
-SLOT_INTERFACE_START(amstr_com)
+static SLOT_INTERFACE_START(amstr_com)
 	SLOT_INTERFACE("microsoft_mouse", MSFT_SERIAL_MOUSE)
 	SLOT_INTERFACE("mouse_systems_mouse", MSYSTEM_SERIAL_MOUSE)
 SLOT_INTERFACE_END
diff --git a/src/mess/drivers/pc.c b/src/mess/drivers/pc.c
index b172748d409..04bb67aa916 100644
--- a/src/mess/drivers/pc.c
+++ b/src/mess/drivers/pc.c
@@ -944,7 +944,7 @@ static SLOT_INTERFACE_START( mc1502_floppies )
 		SLOT_INTERFACE( "525qd", FLOPPY_525_QD )
 SLOT_INTERFACE_END
 
-SLOT_INTERFACE_START(ibm5150_com)
+static SLOT_INTERFACE_START(ibm5150_com)
 	SLOT_INTERFACE("microsoft_mouse", MSFT_SERIAL_MOUSE)
 	SLOT_INTERFACE("mouse_systems_mouse", MSYSTEM_SERIAL_MOUSE)
 SLOT_INTERFACE_END