Hi, All! I am using Boost.Test library in my own application and I have included boost/test/unit_test.hpp in many my cpp-files. When I used boost version 1.33.1 all works fine. But in version 1.34 I have following compiler error: file1.obj : error LNK2005: "class unit_test_log_t::boost::unit_test_log_t & boost::unit_test::`anonymous namespace'::unit_test_log" (?unit_test_log@?A0xa35d3712@unit_test@boost@@3AAVunit_test_log_t@23@A) already defined in file2.obj After including boost/test/unit_test.hpp class unit_test_log has multiple instances. See boost/test/unit_test_log.hpp for details: BOOST_TEST_SINGLETON_INST( unit_test_log ) It means that following code will be included in many cpp-files! namespace { unit_test_log_t & inst = unit_test_log_t::instance(); } When I replace BOOST_TEST_SINGLETON_INST( unit_test_log ) in boost/test/unit_test_log.hpp with namespace {extern unit_test_log_t & unit_test_log;} and in one of my cpp-files add: namespace boost { namespace unit_test { BOOST_TEST_SINGLETON_INST( unit_test_log ) } } all works fine May be I do not understand something? Is there any legal workaround from this situation? I do not like touch boost core files by myself. Thank you! VC++ 7.1, boost 1.34, xp sp2.