diff --git a/src/mame/drivers/srmp5.c b/src/mame/drivers/srmp5.c
index e38b2a83235..7db0ca0e01d 100644
--- a/src/mame/drivers/srmp5.c
+++ b/src/mame/drivers/srmp5.c
@@ -389,7 +389,7 @@ static INPUT_PORTS_START( srmp5 )
 	PORT_DIPNAME( 0x0040, 0x0040, "PUT" )
 	PORT_DIPSETTING(      0x0000, DEF_STR( Off ) )
 	PORT_DIPSETTING(      0x0040, DEF_STR( On ) )
-	PORT_DIPNAME( 0x0080, 0x0080, "Unknown" )
+	PORT_DIPNAME( 0x0080, 0x0080, DEF_STR( Unknown ) )
 	PORT_DIPSETTING(      0x0000, DEF_STR( Off ) )
 	PORT_DIPSETTING(      0x0080, DEF_STR( On ) )
 	PORT_BIT( 0xffffff00, IP_ACTIVE_LOW, IPT_UNUSED )