diff --git a/dlls/msacm32/wineacm.h b/dlls/msacm32/wineacm.h
index 117d745..dfe1730 100644
--- a/dlls/msacm32/wineacm.h
+++ b/dlls/msacm32/wineacm.h
@@ -22,6 +22,7 @@
     WINE_ACMOBJ		obj;
     PWINE_ACMDRIVER	pDrv;
     ACMDRVSTREAMINSTANCE drvInst;
+    HACMDRIVER		hAcmDriver;
 } WINE_ACMSTREAM, *PWINE_ACMSTREAM;
 
 typedef struct _WINE_ACMDRIVERID