diff --git a/gtk2_ardour/ardour_ui2.cc b/gtk2_ardour/ardour_ui2.cc
index b112576a5b..83d68875d1 100644
--- a/gtk2_ardour/ardour_ui2.cc
+++ b/gtk2_ardour/ardour_ui2.cc
@@ -141,8 +141,8 @@ ARDOUR_UI::setup_tooltips ()
 	set_tip (solo_alert_button, _("When active, something is soloed.\nClick to de-solo everything"));
 	set_tip (auditioning_alert_button, _("When active, auditioning is taking place\nClick to stop the audition"));
 	set_tip (feedback_alert_button, _("When active, there is a feedback loop."));
-	set_tip (primary_clock, _("Primary Clock"));
-	set_tip (secondary_clock, _("Secondary Clock"));
+	set_tip (primary_clock, _("<b>Primary Clock</b> right-click to set display mode. Click to edit, click+drag a digit or mouse-over+scroll wheel to modify.\nText edits: right-to-left overwrite <tt>Esc</tt>: cancel; <tt>Enter</tt>: confirm; postfix the edit with '+' or '-' to enter delta times.\nSee <span color=\"blue\">http://ardour.org/a3_features_clocks</span> for details."));
+	set_tip (secondary_clock, _("<b>Secondary Clock</b> right-click to set display mode. Click to edit, click+drag a digit or mouse-over+scroll wheel to modify.\nText edits: right-to-left overwrite <tt>Esc</tt>: cancel; <tt>Enter</tt>: confirm; postfix the edit with '+' or '-' to enter delta times.\nSee <span color=\"blue\">http://ardour.org/a3_features_clocks</span> for details."));
 
 	synchronize_sync_source_and_video_pullup ();