diff --git a/src/mame/drivers/mpu4vid.cpp b/src/mame/drivers/mpu4vid.cpp
index 318c703c5b1..2b6ff20aedb 100644
--- a/src/mame/drivers/mpu4vid.cpp
+++ b/src/mame/drivers/mpu4vid.cpp
@@ -875,7 +875,7 @@ static INPUT_PORTS_START( v4psi )
 	PORT_INCLUDE( mpu4 )
 	PORT_MODIFY("ORANGE1")
 	PORT_BIT( 0x07, IP_ACTIVE_HIGH, IPT_UNKNOWN )
-	PORT_BIT( 0x08, IP_ACTIVE_HIGH, IPT_CUSTOM ) // Payout Shelf opto
+	PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_CUSTOM ) // Payout Shelf opto
 	PORT_BIT( 0xf0, IP_ACTIVE_HIGH, IPT_UNKNOWN )
 
 	PORT_MODIFY("ORANGE2")