diff --git a/engines/scumm/imuse/imuse.cpp b/engines/scumm/imuse/imuse.cpp
index 5ad4798578a7..27a72c2afee1 100644
--- a/engines/scumm/imuse/imuse.cpp
+++ b/engines/scumm/imuse/imuse.cpp
@@ -1693,8 +1693,10 @@ void IMuseInternal::copyGlobalInstrument(byte slot, Instrument *dest) {
 		// In case we have an valid instrument set up, copy it to the part.
 		_global_instruments[slot].copy_to(dest);
 	} else if (_pcSpeaker) {
+		debug(0, "Trying to use non-existant global PC Speaker instrument %d", slot);
 		dest->pcspk(defaultInstr);
 	} else {
+		debug(0, "Trying to use non-existant global AdLib instrument %d", slot);
 		dest->adlib(defaultInstr);
 	}
 }