Currently the integer tests report an error on 64 bit platforms, as can be seen on http://tinyurl.com/6whtg The following code in integer_test.cpp causes the problem: PRIVATE_FIT_TESTS( int_t, least, long, LONG_MAX ); PRIVATE_FIT_TESTS( int_t, fast, long, LONG_MAX ); PRIVATE_FIT_TESTS( uint_t, least, unsigned long, ULONG_MAX ); PRIVATE_FIT_TESTS( uint_t, fast, unsigned long, ULONG_MAX ); The first line expands to: do { long v = LONG_MAX ; PRIVATE_FIT_TEST(int_t, 32, least, v); v >>= 1; PRIVATE_FIT_TEST(int_t, 31, least, v); v >>= 1; ... } which becomes: do { long v = LONG_MAX ; BOOST_TEST( int_t < 32 > :: least ( v ) == v ); v >>= 1; BOOST_TEST( int_t < 31 > :: least ( v ) == v ); v >>= 1; ... } which of course alway fails on 64 bit platforms because LONG_MAX is a 64 bit number. A possible fix would be to start the test with 64 bit and not 32 on 64 bit platforms. But how can 64 bit platforms be detected? Probably with #if (LONG_MAX > INT_MAX) ... #endif or something like this. Another fix (which ignores 64 bit values alltogether) would be to change the lines above to not use long and LONG_MAX but int and INT_MAX. Opinions, anyone? Markus