- Convert HDRVR to a void*.
- Fix declaration of DriverCallback().

diff --git a/include/mmsystem.h b/include/mmsystem.h
index 88dd1dc..a24eaab 100644
--- a/include/mmsystem.h
+++ b/include/mmsystem.h
@@ -30,7 +30,7 @@
 typedef LPSTR		HPSTR;          /* a huge version of LPSTR */
 typedef LPCSTR		HPCSTR;         /* a huge version of LPCSTR */
 
-DECLARE_OLD_HANDLE(HDRVR);
+DECLARE_HANDLE(HDRVR);
 DECLARE_HANDLE(HWAVE);
 DECLARE_HANDLE(HWAVEIN);
 DECLARE_HANDLE(HWAVEOUT);