diff --git a/gtk2_ardour/midi_scroomer.cc b/gtk2_ardour/midi_scroomer.cc
index c3295c8f73..0cd7eae46a 100644
--- a/gtk2_ardour/midi_scroomer.cc
+++ b/gtk2_ardour/midi_scroomer.cc
@@ -16,11 +16,11 @@
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
 
-#include "midi_scroomer.h"
-
+#include <iostream>
 #include <cairomm/context.h>
 
-#include <iostream>
+#include "midi_scroomer.h"
+#include "ui_config.h"
 
 using namespace Gtkmm2ext;
 using namespace Gtk;
@@ -164,5 +164,5 @@ MidiScroomer::get_colors(double color[], Component comp)
 void
 MidiScroomer::on_size_request(Gtk::Requisition* r)
 {
-	r->width = 12;
+	r->width = std::max (12.f, rintf (12.f * UIConfiguration::instance().get_ui_scale()));
 }
diff --git a/gtk2_ardour/piano_roll_header.cc b/gtk2_ardour/piano_roll_header.cc
index 043f6c546e..cdd956dddd 100644
--- a/gtk2_ardour/piano_roll_header.cc
+++ b/gtk2_ardour/piano_roll_header.cc
@@ -27,6 +27,7 @@
 #include "midi_time_axis.h"
 #include "midi_streamview.h"
 #include "public_editor.h"
+#include "ui_config.h"
 
 using namespace std;
 using namespace Gtkmm2ext;
@@ -661,7 +662,7 @@ PianoRollHeader::invalidate_note_range(int lowest, int highest)
 void
 PianoRollHeader::on_size_request(Gtk::Requisition* r)
 {
-	r->width = 20;
+	r->width = std::max (20.f, rintf (20.f * UIConfiguration::instance().get_ui_scale()));
 }
 
 void