diff --git a/src/include/switch_platform.h b/src/include/switch_platform.h
index c782dac9f2..beeb1cd18e 100644
--- a/src/include/switch_platform.h
+++ b/src/include/switch_platform.h
@@ -311,6 +311,7 @@ SWITCH_END_EXTERN_C
 #define _Out_
 #define _Check_return_
 #define _Inout_
+#define _Inout_opt_
 #endif