diff --git a/include/msacm.h b/include/msacm.h
index 8e9c85b10a2..a7d00a7fbc0 100644
--- a/include/msacm.h
+++ b/include/msacm.h
@@ -40,6 +40,7 @@ extern "C" {
 #define MM_ACM_CLOSE MM_STREAM_CLOSE
 #define MM_ACM_DONE  MM_STREAM_DONE
 
+#define ACM_DRIVERADDF_NAME       0x00000001L
 #define ACM_DRIVERADDF_FUNCTION   0x00000003L
 #define ACM_DRIVERADDF_NOTIFYHWND 0x00000004L
 #define ACM_DRIVERADDF_TYPEMASK   0x00000007L