diff --git a/src/gui/midi.cpp b/src/gui/midi.cpp
index 57181e00..d7a0c472 100644
--- a/src/gui/midi.cpp
+++ b/src/gui/midi.cpp
@@ -130,7 +130,7 @@ void MIDI_RawOutByte(Bit8u data) {
 				}
 			}
 
-			LOG(LOG_ALL,LOG_NORMAL)("Sysex message size %d",midi.sysex.used);
+			LOG(LOG_ALL,LOG_NORMAL)("Sysex message size %d", static_cast<int>(midi.sysex.used));
 			if (CaptureState & CAPTURE_MIDI) {
 				CAPTURE_AddMidi( true, midi.sysex.used-1, &midi.sysex.buf[1]);
 			}