diff --git a/md5.c b/md5.c
index 13f8455..fd25282 100644
--- a/md5.c
+++ b/md5.c
@@ -52,6 +52,7 @@
 
 #include <string.h>
 #include <stdio.h>
+#include <endian.h>
 
 #include "md5.h"