diff --git a/libs/widgets/ardour_button.cc b/libs/widgets/ardour_button.cc
index 73a11d9725..663344aed4 100644
--- a/libs/widgets/ardour_button.cc
+++ b/libs/widgets/ardour_button.cc
@@ -238,6 +238,13 @@ ArdourButton::set_sizing_text (std::string const& str)
 	queue_resize ();
 }
 
+void
+ArdourButton::add_sizing_text (std::string const& str)
+{
+	_sizing_texts.push_back (str);
+	queue_resize ();
+}
+
 void
 ArdourButton::set_sizing_texts (std::vector<std::string> const& s)
 {
diff --git a/libs/widgets/widgets/ardour_button.h b/libs/widgets/widgets/ardour_button.h
index 7b39f6c5bf..250e4b305b 100644
--- a/libs/widgets/widgets/ardour_button.h
+++ b/libs/widgets/widgets/ardour_button.h
@@ -113,6 +113,7 @@ class LIBWIDGETS_API ArdourButton : public CairoWidget , public Gtkmm2ext::Activ
      * empty string to return to the default behavior which uses
      * the currently displayed text for measurement. */
 	void set_sizing_text (std::string const&);
+	void add_sizing_text (std::string const&);
 	void set_sizing_texts (std::vector<std::string> const&);
 
 	sigc::signal<void, GdkEventButton*> signal_led_clicked;