diff --git a/apple2sdl/sdlSpeaker.go b/apple2sdl/sdlSpeaker.go
index 42bd7ce..d26adcf 100644
--- a/apple2sdl/sdlSpeaker.go
+++ b/apple2sdl/sdlSpeaker.go
@@ -58,6 +58,7 @@ func stateToLevel(state bool) C.Uint8 {
 	return 0
 }
 
+// SpeakerCallback is called to get more sound buffer data
 //export SpeakerCallback
 func SpeakerCallback(userdata unsafe.Pointer, stream *C.Uint8, length C.int) {
 	s := theSDLSpeaker