diff --git a/include/sal.h b/include/sal.h
index 823361af17e..81a828dd977 100644
--- a/include/sal.h
+++ b/include/sal.h
@@ -97,6 +97,7 @@
 #define _Inout_updates_(count)
 #define _Inout_updates_bytes_(count)
 #define _Inout_updates_bytes_all_opt_(count)
+#define _Inout_updates_bytes_opt_(count)
 #define _Inout_updates_opt_(count)
 #define _Inout_updates_z_(count)
 #define _Inout_updates_opt_z_(count)