diff --git a/libs/ardour/delivery.cc b/libs/ardour/delivery.cc
index 1566f7877d..72429e472d 100644
--- a/libs/ardour/delivery.cc
+++ b/libs/ardour/delivery.cc
@@ -454,6 +454,10 @@ Delivery::flush_buffers (framecnt_t nframes, framepos_t time)
 {
 	/* io_lock, not taken: function must be called from Session::process() calltree */
 
+	if (!_output) {
+		return;
+	}
+	
 	PortSet& ports (_output->ports());
 
 	for (PortSet::iterator i = ports.begin(); i != ports.end(); ++i) {
diff --git a/libs/ardour/midi_track.cc b/libs/ardour/midi_track.cc
index d51e5ef067..fe2dc74b72 100644
--- a/libs/ardour/midi_track.cc
+++ b/libs/ardour/midi_track.cc
@@ -398,7 +398,12 @@ MidiTrack::roll (pframes_t nframes, framepos_t start_frame, framepos_t end_frame
 		                        (!diskstream->record_enabled() && !_session.transport_stopped()));
 	}
 
-	_main_outs->flush_buffers (nframes, end_frame - start_frame - 1);
+	for (ProcessorList::iterator i = _processors.begin(); i != _processors.end(); ++i) {
+		boost::shared_ptr<Delivery> d = boost::dynamic_pointer_cast<Delivery> (*i);
+		if (d) {
+			d->flush_buffers (nframes, end_frame - start_frame - 1);
+		}
+	}
 
 	return 0;
 }
diff --git a/libs/ardour/track.cc b/libs/ardour/track.cc
index 4f682085b2..5c9bcc747d 100644
--- a/libs/ardour/track.cc
+++ b/libs/ardour/track.cc
@@ -278,7 +278,12 @@ Track::no_roll (pframes_t nframes, framepos_t start_frame, framepos_t end_frame,
 		passthru (start_frame, end_frame, nframes, false);
 	}
 
-	_main_outs->flush_buffers (nframes, end_frame - start_frame - 1);
+	for (ProcessorList::iterator i = _processors.begin(); i != _processors.end(); ++i) {
+		boost::shared_ptr<Delivery> d = boost::dynamic_pointer_cast<Delivery> (*i);
+		if (d) {
+			d->flush_buffers (nframes, end_frame - start_frame - 1);
+		}
+	}
 
 	return 0;
 }