AMDG Does Boost.Filesystem have any support at all for cygwin paths? I know that you want to use Windows paths internally, but this creates problems for programs that get paths from an external source. In particular, it causes the regression tests to fail when running from cygwin. See https://github.com/boostorg/regression/issues/37. else if ( !locate_root.is_complete() ) { locate_root = ( fs::initial_path() / locate_root ).normalize(); } locate_root is created by locate_root = fs::path( *args_i ); i.e. it's taken directly from the command line. In Christ, Steven Watanabe