diff --git a/libs/ardour/port_manager.cc b/libs/ardour/port_manager.cc
index 4cae0d5c69..03c3a31000 100644
--- a/libs/ardour/port_manager.cc
+++ b/libs/ardour/port_manager.cc
@@ -1004,6 +1004,10 @@ PortManager::connect_callback (const string& a, const string& b, bool conn)
 		}
 	}
 
+	if (!port_a && !port_b && Config->get_restore_hardware_connections () && !AudioEngine::instance ()->is_jack ()) {
+		AudioEngine::instance ()->session ()->set_dirty ();
+	}
+
 	PortConnectedOrDisconnected (
 	    port_a, a,
 	    port_b, b,