diff --git a/src/sound/win32_s.cpp b/src/sound/win32_s.cpp
--- a/src/sound/win32_s.cpp
+++ b/src/sound/win32_s.cpp
@@ -1,5 +1,7 @@
 /* $Id$ */
 
+/** @file win32_s.cpp Handling of sound for Windows. */
+
 #include "../stdafx.h"
 #include "../openttd.h"
 #include "../driver.h"