diff --git a/include/nuttx/streams.h b/include/nuttx/streams.h
index 32efd999784..63fb83f2c30 100644
--- a/include/nuttx/streams.h
+++ b/include/nuttx/streams.h
@@ -476,7 +476,7 @@ int lib_vsprintf(FAR struct lib_outstream_s *obj,
  ****************************************************************************/
 
 int lib_vscanf(FAR struct lib_instream_s *obj, FAR int *lastc,
-               FAR const IPTR char *src, va_list ap);
+               FAR const IPTR char *src, va_list ap) scanflike(3, 0);
 
 #undef EXTERN
 #if defined(__cplusplus)