diff --git a/libs/ardour/ardour/midi_port.h b/libs/ardour/ardour/midi_port.h
index d3e3e88f3b..16a8d1ae81 100644
--- a/libs/ardour/ardour/midi_port.h
+++ b/libs/ardour/ardour/midi_port.h
@@ -59,7 +59,7 @@ class LIBARDOUR_API MidiPort : public Port {
 
 	MidiBuffer& get_midi_buffer (pframes_t nframes);
 
-	void set_trace (MIDI::Parser* trace_parser);
+	void set_trace (std::weak_ptr<MIDI::Parser> trace_parser);
 
 	typedef boost::function<bool(MidiBuffer&,MidiBuffer&)> MidiFilter;
 	void set_inbound_filter (MidiFilter);
@@ -80,7 +80,7 @@ private:
 	MidiFilter                  _inbound_midi_filter;
 	std::shared_ptr<MidiPort> _shadow_port;
 	MidiFilter                  _shadow_midi_filter;
-	MIDI::Parser*               _trace_parser;
+	std::weak_ptr<MIDI::Parser> _trace_parser;
 	bool                        _data_fetched_for_cycle;
 
 	void resolve_notes (void* buffer, samplepos_t when);
diff --git a/libs/ardour/ardour/triggerbox.h b/libs/ardour/ardour/triggerbox.h
index 89f4ca0c23..afcb333bbe 100644
--- a/libs/ardour/ardour/triggerbox.h
+++ b/libs/ardour/ardour/triggerbox.h
@@ -934,7 +934,7 @@ class LIBARDOUR_API TriggerBox : public Processor
 	static CustomMidiMap _custom_midi_map;
 
 	static void midi_input_handler (MIDI::Parser&, MIDI::byte*, size_t, samplecnt_t);
-	static MIDI::Parser* input_parser;
+	static std::shared_ptr<MIDI::Parser> input_parser;
 	static PBD::ScopedConnection midi_input_connection;
 	static void input_port_check ();
 	static PBD::ScopedConnectionList static_connections;
diff --git a/libs/ardour/midi_port.cc b/libs/ardour/midi_port.cc
index d0fce0300e..c9ee413b93 100644
--- a/libs/ardour/midi_port.cc
+++ b/libs/ardour/midi_port.cc
@@ -43,7 +43,6 @@ MidiPort::MidiPort (const std::string& name, PortFlags flags)
 	: Port (name, DataType::MIDI, flags)
 	, _resolve_required (false)
 	, _input_active (true)
-	, _trace_parser (0)
 	, _data_fetched_for_cycle (false)
 {
 	_buffer = new MidiBuffer (AudioEngine::instance()->raw_buffer_size (DataType::MIDI));
@@ -75,8 +74,11 @@ MidiPort::cycle_start (pframes_t nframes)
 		port_engine.midi_clear (port_engine.get_buffer (_port_handle, nframes));
 	}
 
-	if (receives_input() && _trace_parser) {
-		read_and_parse_entire_midi_buffer_with_no_speed_adjustment (nframes, *_trace_parser, AudioEngine::instance()->sample_time_at_cycle_start());
+	if (receives_input()) {
+		std::shared_ptr<MIDI::Parser> trace_parser = _trace_parser.lock ();
+		if (trace_parser) {
+			read_and_parse_entire_midi_buffer_with_no_speed_adjustment (nframes, *trace_parser.get(), AudioEngine::instance()->sample_time_at_cycle_start());
+		}
 	}
 
 	if (_inbound_midi_filter) {
@@ -293,16 +295,19 @@ MidiPort::flush_buffers (pframes_t nframes)
 
 			const samplepos_t adjusted_time = ev.time() + _global_port_buffer_offset;
 
-			if (sends_output() && _trace_parser) {
-				uint8_t const * const buf = ev.buffer();
-				const samplepos_t now = AudioEngine::instance()->sample_time_at_cycle_start();
+			if (sends_output()) {
+				std::shared_ptr<MIDI::Parser> trace_parser = _trace_parser.lock ();
+				if (trace_parser) {
+					uint8_t const * const buf = ev.buffer();
+					const samplepos_t now = AudioEngine::instance()->sample_time_at_cycle_start();
 
-				_trace_parser->set_timestamp (now + adjusted_time / speed_ratio);
+					trace_parser->set_timestamp (now + adjusted_time / speed_ratio);
 
-				uint32_t limit = ev.size();
+					uint32_t limit = ev.size();
 
-				for (size_t n = 0; n < limit; ++n) {
-					_trace_parser->scanner (buf[n]);
+					for (size_t n = 0; n < limit; ++n) {
+						trace_parser->scanner (buf[n]);
+					}
 				}
 			}
 
@@ -386,7 +391,7 @@ MidiPort::reset ()
 }
 
 void
-MidiPort::set_trace (MIDI::Parser * p)
+MidiPort::set_trace (std::weak_ptr<MIDI::Parser> p)
 {
 	_trace_parser = p;
 }
diff --git a/libs/ardour/triggerbox.cc b/libs/ardour/triggerbox.cc
index b247eb0f72..c161c59ff4 100644
--- a/libs/ardour/triggerbox.cc
+++ b/libs/ardour/triggerbox.cc
@@ -3049,7 +3049,7 @@ TriggerBox::CustomMidiMap TriggerBox::_custom_midi_map;
 std::pair<int,int> TriggerBox::learning_for;
 PBD::Signal0<void> TriggerBox::TriggerMIDILearned;
 
-MIDI::Parser* TriggerBox::input_parser (new MIDI::Parser); /* leak */
+std::shared_ptr<MIDI::Parser> TriggerBox::input_parser;
 PBD::ScopedConnectionList TriggerBox::static_connections;
 PBD::ScopedConnection TriggerBox::midi_input_connection;
 std::shared_ptr<MidiPort> TriggerBox::current_input;
@@ -3068,6 +3068,7 @@ TriggerBox::init ()
 void
 TriggerBox::static_init (Session & s)
 {
+	input_parser = std::shared_ptr<MIDI::Parser>(new MIDI::Parser); /* leak */
 	Config->ParameterChanged.connect_same_thread (static_connections, boost::bind (&TriggerBox::static_parameter_changed, _1));
 	input_parser->any.connect_same_thread (midi_input_connection, boost::bind (&TriggerBox::midi_input_handler, _1, _2, _3, _4));
 	std::dynamic_pointer_cast<MidiPort> (s.trigger_input_port())->set_trace (input_parser);