diff --git a/libs/ardour/ardour/types.h b/libs/ardour/ardour/types.h
index 49401cfd4c..3246d1b169 100644
--- a/libs/ardour/ardour/types.h
+++ b/libs/ardour/ardour/types.h
@@ -732,7 +732,8 @@ enum PortFlags {
 
 	/* non-JACK related flags */
 	Hidden = 0x20,
-	Shadow = 0x40
+	Shadow = 0x40,
+	TransportMasterPort = 0x80
 };
 
 enum MidiPortFlags {