diff --git a/src/mame/drivers/gaelco3d.c b/src/mame/drivers/gaelco3d.c
index 75a3a02e2d6..a8ddab47f13 100644
--- a/src/mame/drivers/gaelco3d.c
+++ b/src/mame/drivers/gaelco3d.c
@@ -362,7 +362,7 @@ static READ32_HANDLER( input_port_3_020_r ) { return readinputport(3) << 16; }
 
 static CUSTOM_INPUT( analog_bit_r )
 {
-	int which = (FPTR)machine;
+	int which = (FPTR)param;
 	return (analog_ports[which] >> 7) & 0x01;
 }