diff --git a/include/sal.h b/include/sal.h
index 72803a1be39..d49f6308327 100644
--- a/include/sal.h
+++ b/include/sal.h
@@ -89,6 +89,7 @@
 #define _Inout_
 #define _Inout_bytecap_x_(count)
 #define _Inout_cap_(count)
+#define _Inout_cap_c_(count)
 #define _Inout_opt_
 #define _Inout_opt_cap_c_(count)
 #define _Inout_opt_z_