diff --git a/libs/ardour/midi_port.cc b/libs/ardour/midi_port.cc
index 1377938f2e..b34ebb5187 100644
--- a/libs/ardour/midi_port.cc
+++ b/libs/ardour/midi_port.cc
@@ -205,7 +205,7 @@ MidiPort::flush_buffers (pframes_t nframes)
 #ifndef NDEBUG
 	if (DEBUG::MidiIO & PBD::debug_bits) {
 		DEBUG_STR_DECL(a);
-		DEBUG_STR_APPEND(a, string_compose ("MidiPort %1 pop event    @ %2 sz %3 ", this, ev.time(), ev.size()));
+		DEBUG_STR_APPEND(a, string_compose ("MidiPort %1 pop event    @ %2 sz %3 ", _buffer, ev.time(), ev.size()));
 		for (size_t i=0; i < ev.size(); ++i) {
 			DEBUG_STR_APPEND(a,hex);
 			DEBUG_STR_APPEND(a,"0x");