diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index ff58eb0f81..99da5ea63a 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -3541,6 +3541,7 @@ Route::set_active (bool yn, void* src)
 		_input->set_active (yn);
 		_output->set_active (yn);
 		active_changed (); // EMIT SIGNAL
+		_session.set_dirty ();
 	}
 }