diff --git a/include/nuttx/streams.h b/include/nuttx/streams.h
index c8f825d669000..32efd99978438 100644
--- a/include/nuttx/streams.h
+++ b/include/nuttx/streams.h
@@ -452,7 +452,7 @@ int lib_snoflush(FAR struct lib_sostream_s *this);
  ****************************************************************************/
 
 int lib_sprintf(FAR struct lib_outstream_s *obj,
-                FAR const IPTR char *fmt, ...);
+                FAR const IPTR char *fmt, ...) printflike(2, 3);
 
 /****************************************************************************
  * Name: lib_vsprintf
@@ -464,7 +464,7 @@ int lib_sprintf(FAR struct lib_outstream_s *obj,
  ****************************************************************************/
 
 int lib_vsprintf(FAR struct lib_outstream_s *obj,
-                 FAR const IPTR char *src, va_list ap);
+                 FAR const IPTR char *src, va_list ap) printflike(2, 0);
 
 /****************************************************************************
  * Name: lib_vscanf