diff --git a/gtk2_ardour/triggerbox_ui.cc b/gtk2_ardour/triggerbox_ui.cc
index 7037b086e3..fc2ae374b7 100644
--- a/gtk2_ardour/triggerbox_ui.cc
+++ b/gtk2_ardour/triggerbox_ui.cc
@@ -36,8 +36,8 @@ using namespace ArdourCanvas;
 using namespace Gtkmm2ext;
 using namespace PBD;
 
-TriggerEntry::TriggerEntry (Item* parent, ARDOUR::Trigger& t)
-	: Rectangle (parent)
+TriggerEntry::TriggerEntry (Canvas* canvas, ARDOUR::Trigger& t)
+	: Rectangle (canvas)
 	, _trigger (t)
 {
 	const double scale = UIConfiguration::instance().get_ui_scale();
@@ -110,7 +110,9 @@ TriggerBoxUI::build ()
 			break;
 		}
 		std::cerr << "NEW TE for trigger " << n << std::endl;
-		TriggerEntry* te = new TriggerEntry (this, *t);
+		TriggerEntry* te = new TriggerEntry (canvas(), *t);
+		te->set_pack_options (PackOptions (PackFill|PackExpand));
+		add (te);
 
 		_slots.push_back (te);
 
diff --git a/gtk2_ardour/triggerbox_ui.h b/gtk2_ardour/triggerbox_ui.h
index 59781f02ea..b351ed3d35 100644
--- a/gtk2_ardour/triggerbox_ui.h
+++ b/gtk2_ardour/triggerbox_ui.h
@@ -40,7 +40,7 @@ namespace ArdourCanvas {
 class TriggerEntry : public ArdourCanvas::Rectangle
 {
   public:
-	TriggerEntry (ArdourCanvas::Item* parent, ARDOUR::Trigger&);
+	TriggerEntry (ArdourCanvas::Canvas* canvas, ARDOUR::Trigger&);
 	~TriggerEntry ();
 
 	ARDOUR::Trigger& trigger() const { return _trigger; }