diff --git a/gtk2_ardour/ardour_ui_ed.cc b/gtk2_ardour/ardour_ui_ed.cc
index ca23560c7c..3f0bb44336 100644
--- a/gtk2_ardour/ardour_ui_ed.cc
+++ b/gtk2_ardour/ardour_ui_ed.cc
@@ -416,7 +416,7 @@ if (Profile->get_mixbus())
 	ActionManager::session_sensitive_actions.push_back (act);
 	act = ActionManager::register_toggle_action (transport_actions, X_("ToggleTimeMaster"), _("Time Master"), sigc::mem_fun(*this, &ARDOUR_UI::toggle_time_master));
 	ActionManager::session_sensitive_actions.push_back (act);
-	act = ActionManager::register_toggle_action (transport_actions, X_("ToggleExternalSync"), "", sigc::mem_fun(*this, &ARDOUR_UI::toggle_external_sync));
+	act = ActionManager::register_toggle_action (transport_actions, X_("ToggleExternalSync"), _("Use External Positional Sync Source"), sigc::mem_fun(*this, &ARDOUR_UI::toggle_external_sync));
 	ActionManager::session_sensitive_actions.push_back (act);
 
 	for (int i = 1; i <= 32; ++i) {