diff --git a/package/utils/otrx/src/otrx.c b/package/utils/otrx/src/otrx.c
index 2f305cf484..a2bc29f59a 100644
--- a/package/utils/otrx/src/otrx.c
+++ b/package/utils/otrx/src/otrx.c
@@ -9,6 +9,7 @@
  * any later version.
  */
 
+#include <byteswap.h>
 #include <errno.h>
 #include <stdint.h>
 #include <stdio.h>