Hi, I'm trying to emulate the following example using Visual Studio 10. In one file I have: --------- #ifndef QW #define QW #ifdef WIN32 #define BOOST_ALL_DYN_LINK // Force boost to use shared libraries #endif #define BOOST_TEST_MAIN #include <boost/test/unit_test.hpp> #endif // include guard -------------- By itself this compiles and runs, correctly reporting that there is an empty test tree. In a second file, Test1.cpp , I have: ----------------- #include <boost/test/unit_test.hpp> #ifdef WIN32 #define BOOST_ALL_DYN_LINK // Force boost to use shared libraries #endif BOOST_AUTO_TEST_CASE(Test1) { BOOST_REQUIRE(true); } -------------------------- Compiling now leads to the error below(I use multithreaded debug ddl for the project). Is there anything obvious I'm doing wrong? Thx, Marc boost_unit_test_framework-vc100-mt-gd-1_47.lib(boost_unit_test_framework-vc100-mt-gd-1_47.dll) : error LNK2005: "public: static class boost::unit_test::unit_test_log_t & __cdecl boost::unit_test::singleton<class boost::unit_test::unit_test_log_t>::instance(void)" (?instance@?$singleton@Vunit_test_log_t@unit_test@boost@@@unit_test@boost@@SAAAVunit_test_log_t@23@XZ) already defined in Test1.obj 5