When I try to build boost 1_33_1 with mingw ( gcc 3.4.2 ) some libraries don't link properly. At the end of the build process, the following files are missing : boost_filesystem-mgw-1_33_1.dll boost_filesystem-mgw-1_33_1.lib boost_filesystem-mgw-d-1_33_1.dll boost_filesystem-mgw-d-1_33_1.lib boost_filesystem-mgw-d.lib boost_filesystem-mgw-mt-1_33_1.dll boost_filesystem-mgw-mt-1_33_1.lib boost_filesystem-mgw-mt-d-1_33_1.dll boost_filesystem-mgw-mt-d-1_33_1.lib boost_filesystem-mgw-mt-d.lib boost_filesystem-mgw-mt.lib boost_filesystem-mgw.lib boost_serialization-mgw-1_33_1.dll boost_serialization-mgw-1_33_1.lib boost_serialization-mgw-d-1_33_1.dll boost_serialization-mgw-d-1_33_1.lib boost_serialization-mgw-d.lib boost_serialization-mgw-mt-1_33_1.dll boost_serialization-mgw-mt-1_33_1.lib boost_serialization-mgw-mt-d-1_33_1.dll boost_serialization-mgw-mt-d-1_33_1.lib boost_serialization-mgw-mt-d.lib boost_serialization-mgw-mt.lib boost_serialization-mgw.lib boost_signals-mgw-1_33_1.dll boost_signals-mgw-1_33_1.lib boost_signals-mgw-d-1_33_1.dll boost_signals-mgw-d-1_33_1.lib boost_signals-mgw-d.lib boost_signals-mgw-mt-1_33_1.dll boost_signals-mgw-mt-1_33_1.lib boost_signals-mgw-mt-d-1_33_1.dll boost_signals-mgw-mt-d-1_33_1.lib boost_signals-mgw-mt-d.lib boost_signals-mgw-mt.lib boost_signals-mgw.lib I believe that all the other libraries are building successfully. Here are the first few errors that appear in my build log: gcc-Link-action bin\boost\libs\filesystem\build\boost_filesystem.dll\mingw\debug\boost_filesystem-mgw-d-1_33_1.dll bin\boost\libs\filesystem\build\boost_filesystem.dll\mingw\debug\boost_filesystem-mgw-d-1_33_1.lib Creating library file: bin\boost\libs\filesystem\build\boost_filesystem.dll\mingw\debug\boost_filesystem-mgw-d-1_33_1.lib bin\boost\libs\filesystem\build\boost_filesystem.dll\mingw\debug\operations_posix_windows.obj(.text+0x7ac): In function `ZN5boost10filesystem6detail12dir_itr_initERNS_10shared_ptrINS1_11dir_itr_impEEERKNS0_4pathE': c:/cygwin_home/dave/devl/thirdParty/Cygwin/boost/boost_1_33_1x/src/boost_1_33_1/libs/filesystem/build/../src/operations_posix_windows.cpp:308: undefined reference to `boost::filesystem::detail::system_error_code()' bin\boost\libs\filesystem\build\boost_filesystem.dll\mingw\debug\operations_posix_windows.obj(.text+0x81d):c:/cygwin_home/dave/devl/thirdParty/Cygwin/boost/boost_1_33_1x/src/boost_1_33_1/libs/filesystem/build/../src/operations_posix_windows.cpp:308: undefined reference to `boost::filesystem::filesystem_error::filesystem_error(std::string const&, boost::filesystem::path const&, int)' bin\boost\libs\filesystem\build\boost_filesystem.dll\mingw\debug\operations_posix_windows.obj(.text+0x8d7):c:/cygwin_home/dave/devl/thirdParty/Cygwin/boost/boost_1_33_1x/src/boost_1_33_1/libs/filesystem/build/../src/operations_posix_windows.cpp:308: undefined reference to `boost::filesystem::filesystem_error::~filesystem_error()' bin\boost\libs\filesystem\build\boost_filesystem.dll\mingw\debug\operations_posix_windows.obj(.text+0x8f3):c:/cygwin_home/dave/devl/thirdParty/Cygwin/boost/boost_1_33_1x/src/boost_1_33_1/libs/filesystem/build/../src/operations_posix_windows.cpp:308: undefined reference to `boost::filesystem::filesystem_error::~filesystem_error()' So far my work around has been to use 1_33_0 which builds 100% cleanly. Does anyone have any idea either what I might be doing wrong or what is going wrong otherwise. Thanks. - Dave