diff --git a/include/wx/osx/sound.h b/include/wx/osx/sound.h
index 8f9f3edd37..e41636b1ef 100644
--- a/include/wx/osx/sound.h
+++ b/include/wx/osx/sound.h
@@ -17,7 +17,7 @@
 
 #include "wx/object.h"
 
-class WXDLLIMPEXP_ADV wxSoundTimer;
+class WXDLLIMPEXP_FWD_ADV wxSoundTimer;
 
 class WXDLLIMPEXP_ADV wxSoundData
 {