diff --git a/gtk2_ardour/ardour_ui_options.cc b/gtk2_ardour/ardour_ui_options.cc
index 90f24a4434..de19a8d5af 100644
--- a/gtk2_ardour/ardour_ui_options.cc
+++ b/gtk2_ardour/ardour_ui_options.cc
@@ -398,8 +398,10 @@ ARDOUR_UI::parameter_changed (std::string p)
 			secondary_clock->set_widget_name ("secondary");
 		}
 	} else if (p == "super-rapid-clock-update") {
-		stop_clocking ();
-		start_clocking ();
+		if (_session) {
+			stop_clocking ();
+			start_clocking ();
+		}
 	} else if (p == "waveform-gradient-depth") {
 		ArdourCanvas::WaveView::set_global_gradient_depth (config()->get_waveform_gradient_depth());
 	} else if (p == "show-editor-meter") {