diff --git a/libs/ardour/route_group.cc b/libs/ardour/route_group.cc
index 519c88c84f..291806c8cb 100644
--- a/libs/ardour/route_group.cc
+++ b/libs/ardour/route_group.cc
@@ -155,6 +155,10 @@ RouteGroup::~RouteGroup ()
 int
 RouteGroup::add (boost::shared_ptr<Route> r)
 {
+	if (r->is_master()) {
+		return 0;
+	}
+
 	if (find (routes->begin(), routes->end(), r) != routes->end()) {
 		return 0;
 	}