diff --git a/gtk2_ardour/port_matrix.cc b/gtk2_ardour/port_matrix.cc
index 9a22ed97e6..bf9da544e6 100644
--- a/gtk2_ardour/port_matrix.cc
+++ b/gtk2_ardour/port_matrix.cc
@@ -610,6 +610,7 @@ PortMatrix::disassociate_all_on_channel (boost::weak_ptr<Bundle> bundle, uint32_
 void
 PortMatrix::setup_global_ports ()
 {
+	if (!_session || _session->deletion_in_progress()) return;
 	ENSURE_GUI_THREAD (*this, &PortMatrix::setup_global_ports)
 
 	for (int i = 0; i < 2; ++i) {