diff --git a/gtk2_ardour/big_clock_window.cc b/gtk2_ardour/big_clock_window.cc
index 28b7b286ab..d625b87dec 100644
--- a/gtk2_ardour/big_clock_window.cc
+++ b/gtk2_ardour/big_clock_window.cc
@@ -103,7 +103,7 @@ BigClockWindow::on_size_allocate (Gtk::Allocation& alloc)
 void
 BigClockWindow::reset_aspect_ratio ()
 {
-	Gtk::Requisition req;
+	Gtk::Requisition req = { 0, 0 };
 
 	clock.size_request (req);
 
diff --git a/gtk2_ardour/editor_canvas.cc b/gtk2_ardour/editor_canvas.cc
index 482ada3cbc..1bd6ba3d9e 100644
--- a/gtk2_ardour/editor_canvas.cc
+++ b/gtk2_ardour/editor_canvas.cc
@@ -322,7 +322,7 @@ Editor::track_canvas_viewport_size_allocated ()
 void
 Editor::reset_controls_layout_width ()
 {
-	GtkRequisition req;
+	GtkRequisition req = { 0, 0 };
 	gint w;
 
 	edit_controls_vbox.size_request (req);
diff --git a/libs/canvas/widget.cc b/libs/canvas/widget.cc
index 17d0d29e59..25541c1660 100644
--- a/libs/canvas/widget.cc
+++ b/libs/canvas/widget.cc
@@ -91,7 +91,7 @@ Widget::compute_bounding_box () const
 {
 	std::cerr << "cbbox for widget\n";
 
-	GtkRequisition req;
+	GtkRequisition req = { 0, 0 };
 	Gtk::Allocation alloc;
 
 	_widget.size_request (req);