diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index ac3f05e323..f1e3b19732 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -5997,6 +5997,12 @@ Session::next_control_id () const
 		subtract++;
 	}
 
+	/* the same about masterbus in Waves Tracks */
+
+	if (Profile->get_trx() && _master_out) {
+		subtract++;
+	}
+
 	return nroutes() - subtract;
 }