diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 2e93d5d167..7f467dbae3 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -1022,6 +1022,7 @@ Session::remove_monitor_section ()
 	if (auditioner) {
 		auditioner->connect ();
 	}
+	Config->ParameterChanged ("use-monitor-bus");
 }
 
 void
@@ -1173,6 +1174,7 @@ Session::add_monitor_section ()
 	if (auditioner) {
 		auditioner->connect ();
 	}
+	Config->ParameterChanged ("use-monitor-bus");
 }
 
 void