diff --git a/src/headers/tomcrypt_cfg.h b/src/headers/tomcrypt_cfg.h
index ab43978..cb41c9f 100644
--- a/src/headers/tomcrypt_cfg.h
+++ b/src/headers/tomcrypt_cfg.h
@@ -56,7 +56,7 @@ LTC_EXPORT int   LTC_CALL XSTRCMP(const char *s1, const char *s2);
  */
 
 /* detect x86-32 machines somewhat */
-#if !defined(__STRICT_ANSI__) && !defined(_WIN64) && ((defined(_MSC_VER) && defined(WIN32)) || (defined(__GNUC__) && (defined(__DJGPP__) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__i386__))))
+#if !defined(__STRICT_ANSI__) && !defined(__x86_64__) && !defined(_WIN64) && ((defined(_MSC_VER) && defined(WIN32)) || (defined(__GNUC__) && (defined(__DJGPP__) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__i386__))))
    #define ENDIAN_LITTLE
    #define ENDIAN_32BITWORD
    #define LTC_FAST