diff --git a/src/proto/sound.pro b/src/proto/sound.pro
index ad1c2b5..c6d0541 100644
--- a/src/proto/sound.pro
+++ b/src/proto/sound.pro
@@ -1,6 +1,10 @@
 /* sound.c */
+typedef struct soundcb_S soundcb_T;
+
 int has_any_sound_callback(void);
 int has_sound_callback_in_queue(void);
+void call_sound_callback(soundcb_T *soundcb, long sound_id, int result);
+void delete_sound_callback(soundcb_T *soundcb);
 void invoke_sound_callback(void);
 void f_sound_playevent(typval_T *argvars, typval_T *rettv);
 void f_sound_playfile(typval_T *argvars, typval_T *rettv);