diff --git a/libs/ardour/ardour/triggerbox.h b/libs/ardour/ardour/triggerbox.h
index 681d5ba569..a90f4730cb 100644
--- a/libs/ardour/ardour/triggerbox.h
+++ b/libs/ardour/ardour/triggerbox.h
@@ -160,6 +160,7 @@ class LIBARDOUR_API Trigger : public PBD::Stateful {
 	void set_region_internal (boost::shared_ptr<Region>);
 	void request_state (State s);
 	virtual void retrigger() = 0;
+	virtual void set_usable_length () = 0;
 };
 
 class LIBARDOUR_API AudioTrigger : public Trigger {
@@ -177,6 +178,7 @@ class LIBARDOUR_API AudioTrigger : public Trigger {
 
   protected:
 	void retrigger ();
+	void set_usable_length ();
 
   private:
 	std::vector<Sample*> data;
diff --git a/libs/ardour/triggerbox.cc b/libs/ardour/triggerbox.cc
index 728b5a3da8..714f0a0cdb 100644
--- a/libs/ardour/triggerbox.cc
+++ b/libs/ardour/triggerbox.cc
@@ -69,6 +69,8 @@ void
 Trigger::set_launch_style (LaunchStyle l)
 {
 	_launch_style = l;
+
+	set_usable_length ();
 }
 
 XMLNode&
@@ -87,6 +89,7 @@ void
 Trigger::set_quantization (Temporal::BBT_Offset const & q)
 {
 	_quantization = q;
+	set_usable_length ();
 }
 
 void
@@ -414,6 +417,32 @@ AudioTrigger::set_length (timecnt_t const & newlen)
 	}
 }
 
+void
+AudioTrigger::set_usable_length ()
+{
+	if (!_region) {
+		return;
+	}
+
+	switch (_launch_style) {
+	case Repeat:
+		break;
+	default:
+		usable_length = data_length;
+		return;
+	}
+
+	if (_quantization == Temporal::BBT_Offset ()) {
+		usable_length = data_length;
+		return;
+	}
+
+	/* XXX MUST HANDLE BAR-LEVEL QUANTIZATION */
+
+	timecnt_t len (Temporal::Beats (_quantization.beats, _quantization.ticks), timepos_t (Temporal::Beats()));
+	usable_length = len.samples();
+}
+
 timecnt_t
 AudioTrigger::current_length() const
 {