diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 2b602f7398..52b2ad3fe9 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -690,6 +690,8 @@ Session::destroy ()
 
 	/* drop GraphNode references */
 	_graph_chain.reset ();
+	_current_route_graph = GraphEdges ();
+
 	_io_graph_chain[0].reset ();
 	_io_graph_chain[1].reset ();