diff --git a/gtk2_ardour/pianoroll_midi_view.cc b/gtk2_ardour/pianoroll_midi_view.cc
index 9a05616ecf..4d471e8de3 100644
--- a/gtk2_ardour/pianoroll_midi_view.cc
+++ b/gtk2_ardour/pianoroll_midi_view.cc
@@ -201,6 +201,17 @@ PianorollMidiView::set_samples_per_pixel (double spp)
 	reset_width_dependent_items (_editing_context.duration_to_pixels (duration));
 }
 
+void
+PianorollMidiView::reset_width_dependent_items (double pixel_width)
+{
+	MidiView::reset_width_dependent_items (pixel_width);
+
+	for (auto & a : automation_map) {
+		if (a.second.line) {
+			a.second.line->reset ();
+		}
+	}
+}
 void
 PianorollMidiView::clear_ghost_events ()
 {
diff --git a/gtk2_ardour/pianoroll_midi_view.h b/gtk2_ardour/pianoroll_midi_view.h
index df59b4c918..bd4ffaec6a 100644
--- a/gtk2_ardour/pianoroll_midi_view.h
+++ b/gtk2_ardour/pianoroll_midi_view.h
@@ -126,4 +126,6 @@ class PianorollMidiView : public MidiView
 
 	bool midi_canvas_group_event (GdkEvent*);
 	Gtkmm2ext::Color line_color_for (Evoral::Parameter const &);
+
+	void reset_width_dependent_items (double pixel_width);
 };