- (*pi)->xthread().set_receive_handler (sigc::bind (sigc::mem_fun (this, &MidiControlUI::midi_input_handler), *pi));
+ (*pi)->xthread().set_receive_handler (sigc::bind (
+ sigc::mem_fun (this, &MidiControlUI::midi_input_handler), boost::weak_ptr<AsyncMIDIPort>(*pi)));