diff --git a/configure.ac b/configure.ac
index 927319f..9e303fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -54,6 +54,12 @@ AC_FUNC_MALLOC
 AC_FUNC_REALLOC
 AC_FUNC_STRTOD
 AC_CHECK_FUNCS([memchr memmove memset strerror strtol])
+AC_CHECK_DECLS([htole64, le64toh],
+               [],
+               [
+                 AC_CHECK_DECLS([htole64, le64toh], [], [], [#include <endian.h>])
+               ],
+               [#include <sys/endian.h>])
 
 AC_CONFIG_FILES([Makefile
                  src/Makefile
diff --git a/src/endian.c b/src/endian.c
index e620631..b7724f3 100644
--- a/src/endian.c
+++ b/src/endian.c
@@ -19,6 +19,22 @@ void xle64enc(uint8_t *d, uint64_t n) {
 	#include <sys/endian.h>
 #endif
 
+#if !HAVE_DECL_HTOLE64
+# if __BYTE_ORDER == __LITTLE_ENDIAN
+#  define htole64(x) (x)
+# else
+#  define htole64(x) __bswap_64 (x)
+# endif
+#endif
+
+#if !HAVE_DECL_LE64TOH
+# if __BYTE_ORDER == __LITTLE_ENDIAN
+#  define le64toh(x) (x)
+# else
+#  define le64toh(x) __bswap_64 (x)
+# endif
+#endif
+
 uint64_t xle64dec(const uint8_t *d) {
     return le64toh(*(uint64_t*)d);
 }