I've gone thru the exercise of converting all our code to use filesystem v3. Everything worked fine on Windows, but when I tried to compile on Linux and Mac, I get link errors with gcc. I have set my compiler flags to -DBOOST_FILESYSTEM_VERSION=3 and everything compiles fine. All the link errors come from filesystem3: ../NwUtils/libNwUtils.a(FileStream.cpp.o): In function `boost::filesystem3::path& boost::filesystem3::path::append<char [12]>(char const (&) [12], std::codecvt<wchar_t, char, __mbstate_t> const&)': FileStream.cpp:(.text._ZN5boost11filesystem34path6appendIA12_cEERS1_RKT_RKSt 7codecvtIwc11__mbstate_tE[boost::filesystem3::path& boost::filesystem3::path::append<char [12]>(char const (&) [12], std::codecvt<wchar_t, char, __mbstate_t> const&)]+0x30): undefined reference to `boost::filesystem3::path::m_append_separator_if_needed()' FileStream.cpp:(.text._ZN5boost11filesystem34path6appendIA12_cEERS1_RKT_RKSt 7codecvtIwc11__mbstate_tE[boost::filesystem3::path& boost::filesystem3::path::append<char [12]>(char const (&) [12], std::codecvt<wchar_t, char, __mbstate_t> const&)]+0x59): undefined reference to `boost::filesystem3::path::m_erase_redundant_separator(unsigned long)' Am I supposed to compile boost with a different setting to use filesystem v3? I didn't do anything special on windows. When I attempt to build boost on Mac/Linux with -DBOOST_FILESYSTEM_VERSION=3, the boost build fails with errors about BOOST_FILESYSTEM_VERSION != 2. Any help would be greatly appreciated as I'm at my wit's end! Thanks, Scott