diff --git a/libs/ardour/ardour/midiport_manager.h b/libs/ardour/ardour/midiport_manager.h
index 6dd55f998d..87fb8cdde5 100644
--- a/libs/ardour/ardour/midiport_manager.h
+++ b/libs/ardour/ardour/midiport_manager.h
@@ -91,7 +91,7 @@ public:
 	void                set_midi_port_states (const XMLNodeList&);
 	std::list<XMLNode*> get_midi_port_states () const;
 
-	PBD::Signal0<void> PortsChanged;
+	void set_public_latency (bool playback);
 
 protected:
 	/* asynchronously handled ports: ARDOUR::AsyncMIDIPort */
diff --git a/libs/ardour/midiport_manager.cc b/libs/ardour/midiport_manager.cc
index d9050b44b0..ecdb8c9903 100644
--- a/libs/ardour/midiport_manager.cc
+++ b/libs/ardour/midiport_manager.cc
@@ -139,3 +139,27 @@ MidiPortManager::vkbd_output_port () const
 {
 	return boost::dynamic_pointer_cast<AsyncMIDIPort> (_vkbd_out);
 }
+
+void
+MidiPortManager::set_public_latency (bool playback)
+{
+	typedef std::list<boost::shared_ptr<Port> > PortList;
+	PortList pl;
+
+	pl.push_back (_mtc_output_port);
+	pl.push_back (_midi_clock_output_port);
+	pl.push_back (_mmc_in);
+	pl.push_back (_mmc_out);
+	pl.push_back (_vkbd_out);
+	pl.push_back (_scene_out);
+	pl.push_back (_scene_in);
+
+	for (PortList::const_iterator p = pl.begin(); p != pl.end(); ++p) {
+		LatencyRange range;
+		(*p)->get_connected_latency_range (range, playback);
+		/* Ports always align to worst-case latency */
+		range.min = range.max;
+		(*p)->set_private_latency_range (range, playback);
+		(*p)->set_public_latency_range (range, playback);
+	}
+}