diff --git a/include/sal.h b/include/sal.h
index c8b4491fbce..c69f7f9840c 100644
--- a/include/sal.h
+++ b/include/sal.h
@@ -61,6 +61,7 @@
 #define _Inout_updates_bytes_(count)
 #define _Inout_updates_opt_(count)
 #define _Inout_updates_z_(count)
+#define _Inout_updates_opt_z_(count)
 #define _Inout_z_
 #define _Inout_z_bytecap_(count)
 #define _Inout_z_cap_(count)