I'm in the process of updating my code to use filesystem V3. I replaced all the V2 deprecated functions with V3 calls. I defined the macros: BOOST_FILESYSTEM_VERSION=3 BOOST_FILESYSTEM_NO_DEPRECATED When compiling the file libs/filesystem/v3/src/path.cpp I get the following error: #error both BOOST_FILESYSTEM_DEPRECATED and BOOST_FILESYSTEM_NO_DEPRECATED are defined The reason for this error is that in filesystem/v3/config.hpp has the following: // BOOST_FILESYSTEM_DEPRECATED needed for source compiles # ifdef BOOST_FILESYSTEM_SOURCE # define BOOST_FILESYSTEM_DEPRECATED # endif So i'm puzzled as to why BOOST_FILESYSTEM_DEPRECATED is forced when compiling path.cpp? And how can I avoid theses erros when compiling filesystem V3? Thanks Shai Boost version: 1.49 Compiler: gcc version 4.2.1, Xcode 3.2.5 on Mac OS 10.6.8