diff --git a/NanaZip.Codecs/RHash/aich.h b/NanaZip.Codecs/RHash/aich.h
index b1352091..ba784712 100644
--- a/NanaZip.Codecs/RHash/aich.h
+++ b/NanaZip.Codecs/RHash/aich.h
@@ -1,6 +1,7 @@
 /* aich.h */
 #ifndef AICH_H
 #define AICH_H
+#include "byte_order.h"
 #include "sha1.h"
 
 #ifdef __cplusplus