diff --git a/util/cbfstool/flashmap/fmap.c b/util/cbfstool/flashmap/fmap.c
index c152b0dc4e..cb67b46899 100644
--- a/util/cbfstool/flashmap/fmap.c
+++ b/util/cbfstool/flashmap/fmap.c
@@ -1,8 +1,7 @@
 /* SPDX-License-Identifier: BSD-3-Clause or GPL-2.0-only */
 
-#define _XOPEN_SOURCE 700
-
 #include <ctype.h>
+#include <endian.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>