diff --git a/src/fds.c b/src/fds.c
index e5cf7cf..775118a 100644
--- a/src/fds.c
+++ b/src/fds.c
@@ -105,7 +105,7 @@ static void FDSStateRestore(int version) {
 		}
 }
 
-void FDSSound();
+void FDSSound(int a);
 void FDSSoundReset(void);
 void FDSSoundStateAdd(void);
 static void RenderSound(void);