Index: boost/detail/endian.hpp
===================================================================
--- boost/detail/endian.hpp	(revision 74924)
+++ boost/detail/endian.hpp	(working copy)
@@ -43,6 +43,14 @@
 #  error Unknown machine endianness detected.
 # endif
 # define BOOST_BYTE_ORDER __BYTE_ORDER
+#elif defined(__OpenBSD__)
+# include <machine/endian.h>
+# if (_BYTE_ORDER == _LITTLE_ENDIAN)
+#  define BOOST_LITTLE_ENDIAN
+# elif (_BYTE_ORDER == _BIG_ENDIAN)
+#  define BOOST_BIG_ENDIAN
+# endif
+# define BOOST_BYTE_ORDER _BYTE_ORDER
 #elif defined(_BIG_ENDIAN) && !defined(_LITTLE_ENDIAN) || \
     defined(__BIG_ENDIAN__) && !defined(__LITTLE_ENDIAN__) || \
     defined(_STLP_BIG_ENDIAN) && !defined(_STLP_LITTLE_ENDIAN)