diff --git a/gtk2_ardour/editor_canvas.cc b/gtk2_ardour/editor_canvas.cc
index e698110de4..47e3cabe27 100644
--- a/gtk2_ardour/editor_canvas.cc
+++ b/gtk2_ardour/editor_canvas.cc
@@ -313,6 +313,7 @@ Editor::track_canvas_viewport_size_allocated ()
 	}
 
 	update_fixed_rulers();
+	update_tempo_based_rulers ();
 	redisplay_grid (false);
 	_summary->set_overlays_dirty ();
 }
diff --git a/gtk2_ardour/editor_rulers.cc b/gtk2_ardour/editor_rulers.cc
index 99d1ea685f..52aa2eb1ea 100644
--- a/gtk2_ardour/editor_rulers.cc
+++ b/gtk2_ardour/editor_rulers.cc
@@ -679,6 +679,8 @@ Editor::update_tempo_based_rulers ()
 
 	_bbt_metric->units_per_pixel = samples_per_pixel;
 
+	compute_bbt_ruler_scale (_leftmost_sample, _leftmost_sample + current_page_samples());
+
 	if (ruler_bbt_action->get_active()) {
 		bbt_ruler->set_range (_leftmost_sample, _leftmost_sample+current_page_samples());
 	}