I have been using/linking with boost test, 1.39 -->1.45 Boost unit-test has been very robust on the whole However migrating to 1.47 I am getting links errors of the form: ld: 0711-317 ERROR: Undefined symbol: .boost::unit_test::ut_detail::auto_test_unit_registrar::auto_test_unit_registrar(boost::unit_test::basic_cstring<const char>) ld: 0711-317 ERROR: Undefined symbol: .boost::unit_test::unit_test_log_t::set_checkpoint(boost::unit_test::basic_cstring<const char>,unsigned long,boost::unit_test::basic_cstring<const char>) ld: 0711-317 ERROR: Undefined symbol: .boost::test_tools::tt_detail::check_impl(const boost::test_tools::predicate_result&,const boost::unit_test::lazy_ostream&,boost::unit_test::basic_cstring<const char>,unsigned long,boost::test_tools::tt_detail::tool_level,boost::test_tools::tt_detail::check_type,unsigned long,...) ld: 0711-317 ERROR: Undefined symbol: .boost::unit_test::ut_detail::normalize_test_case_name(boost::unit_test::basic_cstring<const char>) ld: 0711-317 ERROR: Undefined symbol: .boost::unit_test::test_case::test_case(boost::unit_test::basic_cstring<const char>,const boost::unit_test::callback0<boost::unit_test::ut_detail::unused>&) The problem is on AIX 5.3. using v11.1 compiler linking with libboost_unit_test_framework-mt-d.a has always worked in the past. The library compiles and links without any errors on other platforms like HPUX/acc,linux32/gcc,linux64/gcc Any help appreciated Best regards, Ta, Avi