diff --git a/gtk2_ardour/midi_time_axis.cc b/gtk2_ardour/midi_time_axis.cc
index 33d192aa1c..6987680f26 100644
--- a/gtk2_ardour/midi_time_axis.cc
+++ b/gtk2_ardour/midi_time_axis.cc
@@ -440,7 +440,11 @@ MidiTimeAxisView::model_changed(const std::string& model)
 		_midnam_custom_device_mode_selector.hide();
 	}
 
-	_route->instrument_info().set_external_instrument (model, device_modes.front());
+	if (device_modes.size() > 0) {
+		_route->instrument_info().set_external_instrument (model, device_modes.front());
+	} else {
+		_route->instrument_info().set_external_instrument (model, "");
+	}
 
 	// Rebuild controller menu
 	_controller_menu_map.clear ();
diff --git a/libs/ardour/ardour/midi_patch_manager.h b/libs/ardour/ardour/midi_patch_manager.h
index 1b7de6a51d..5ed648b3e7 100644
--- a/libs/ardour/ardour/midi_patch_manager.h
+++ b/libs/ardour/ardour/midi_patch_manager.h
@@ -126,10 +126,11 @@ public:
 
 	std::list<std::string> custom_device_mode_names_by_model(std::string model_name) {
 		if (model_name != "") {
-			return master_device_by_model(model_name)->custom_device_mode_names();
-		} else {
-			return std::list<std::string>();
+			if (master_device_by_model(model_name)) {
+				return master_device_by_model(model_name)->custom_device_mode_names();
+			}
 		}
+		return std::list<std::string>();
 	}
 
 	const MasterDeviceNames::Models& all_models() const { return _all_models; }