I've uploaded an adapter allowing filesystem V3 path to be passed to the iostreams library constructors and methods taking paths. I'm using it with boost 1.44 on MSVC8 and Xcode3.1.2 with gcc4.0.1. It currently requires that BOOST_FILESYSTEM_VERSION is defined to be 3, and that users manually use the adapter like: #include <boost/iostreams/device/mapped_file.hpp> #include <boost/iostreams/filesystem_v3_path_adapter.hpp> ... boost::filesystem::path p(...); namespace io = boost::iostreams; io::mapped_file_source mf_src(io::filesystem_v3_path_adapter(p)); Filesystem V3 is deprecated in the upcoming boost 1.47, and will NOT be included in boost 1.48. Has anyone started updating iostreams to account for the removal of filesystem V2? IIRC, Steven Watanabe has been doing some iostreams maintenance. It looks like Jonathan Turkanis is no longer around, is there a new iostreams maintainer? I can take this on if no one else is/has. In my view, and as a few others have stated as well, filesystem V3 path is the common/portable path currency in boost today. The iostreams interface/implementation can be simplified by utilizing path's portability. The windows implementation would always call CreateFileW passing path.wstring().c_str. Thoughts? Thanks, Jeff