Index: src/sim/w_sound.c
--- src/sim/w_sound.c.orig
+++ src/sim/w_sound.c
@@ -145,6 +145,7 @@ static int SoundInitialized = 0;
 Mix_Chunk *rumble;
 
 
+void
 InitializeSound()
 {
   int reserved_chans;
@@ -204,6 +205,7 @@ ShutDownSound()
 }
 
 
+void
 MakeSound(char *channel, char *id)
 {
   char buf[256];
@@ -237,6 +239,7 @@ MakeSound(char *channel, char *id)
     fprintf(stderr, "Mix_PlayChannel: %s\n", Mix_GetError());
 }
 
+void
 StartBulldozer(void)
 {
   if (!UserSoundOn) return;
@@ -249,6 +252,7 @@ StartBulldozer(void)
 }
 
 
+void
 StopBulldozer(void)
 {
   if (!UserSoundOn) return;
@@ -312,6 +316,7 @@ StopBulldozer(void)
 #endif
 
 
+void
 MakeSoundOn(SimView *view, char *channel, char *id)
 {
   if (!UserSoundOn) return;
