The boost unit test framework exports std::basic_ostringstream to the dll. This causes linker errors on visual studio 2012 (LNK 2005), if the tested code contains std::basic_ostringstream. You can confirm the symbol std::basic_ostringstream is in boost_unit_test_framework-vc110-mt-1_61.dll by using dependency walker. I have the same problem with my self-built dlls as well as the ones downloaded from https://sourceforge.net/projects/boost/files/boost-binaries/. Is this a problem with boost or did I configure the build wrong? Thank you. I posted the issue on Stack Overflow a week ago [1]. Please excuse, if this still counts as cross posting. Regards Sascha [1] http://stackoverflow.com/questions/37922117/stdbasic-ostringstream-exported-...