diff --git a/src/mess/drivers/amstrad.c b/src/mess/drivers/amstrad.c
index 08346a70f79..5955a6ec555 100644
--- a/src/mess/drivers/amstrad.c
+++ b/src/mess/drivers/amstrad.c
@@ -650,7 +650,7 @@ static INPUT_PORTS_START( gx4000 )
 	PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_JOYSTICK_RIGHT) PORT_PLAYER(2) PORT_8WAY
 	PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_BUTTON1)        PORT_PLAYER(2)
 	PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_BUTTON2)        PORT_PLAYER(2)
-	PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_UNUSED)
+	PORT_BIT(0xc0, IP_ACTIVE_LOW, IPT_UNUSED)
 
 	PORT_START("keyboard_row_7")
 	PORT_BIT(0xff, IP_ACTIVE_LOW, IPT_UNUSED)
@@ -665,7 +665,7 @@ static INPUT_PORTS_START( gx4000 )
 	PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_JOYSTICK_RIGHT) PORT_PLAYER(1) PORT_8WAY
 	PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_BUTTON1)        PORT_PLAYER(1)
 	PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_BUTTON2)        PORT_PLAYER(1)
-	PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_UNUSED)
+	PORT_BIT(0xc0, IP_ACTIVE_LOW, IPT_UNUSED)
 
 	PORT_INCLUDE(crtc_links)  // included to keep the driver happy