diff --git a/libs/ardour/ardour/triggerbox.h b/libs/ardour/ardour/triggerbox.h
index 98efa0598a..c41ab3ebf0 100644
--- a/libs/ardour/ardour/triggerbox.h
+++ b/libs/ardour/ardour/triggerbox.h
@@ -847,6 +847,7 @@ class LIBARDOUR_API TriggerBox : public Processor, public std::enable_shared_fro
 	RecordState record_enabled() const { return _record_state; }
 	PBD::Signal<void()> RecEnableChanged;
 	static PBD::Signal<void()> TriggerRecEnableChanged;
+	static PBD::Signal<void(Trigger const *)> RegionCaptured;
 
 	void arm_from_another_thread (Trigger& slot, samplepos_t, uint32_t chans, Temporal::BBT_Offset const &);
 	void disarm();
diff --git a/libs/ardour/triggerbox.cc b/libs/ardour/triggerbox.cc
index ae67ea90f7..be365aa76f 100644
--- a/libs/ardour/triggerbox.cc
+++ b/libs/ardour/triggerbox.cc
@@ -1772,6 +1772,10 @@ AudioTrigger::set_region_in_worker_thread_internal (std::shared_ptr<Region> r, b
 
 	send_property_change (ARDOUR::Properties::region);
 
+	if (from_capture) {
+		box().RegionCaptured (this);
+	}
+
 	return 0;
 }
 
@@ -2968,6 +2972,8 @@ MIDITrigger::set_region_in_worker_thread_from_capture (std::shared_ptr<Region> r
 
 	send_property_change (ARDOUR::Properties::region);
 
+	box().RegionCaptured (this);
+
 	return 0;
 }
 
@@ -3513,6 +3519,7 @@ TriggerBoxThread* TriggerBox::worker = 0;
 CueRecords TriggerBox::cue_records (256);
 std::atomic<bool> TriggerBox::_cue_recording (false);
 PBD::Signal<void()> TriggerBox::CueRecordingChanged;
+PBD::Signal<void(Trigger const *)> TriggerBox::RegionCaptured;
 bool TriggerBox::roll_requested = false;
 bool TriggerBox::_learning = false;
 TriggerBox::CustomMidiMap TriggerBox::_custom_midi_map;