Hello, In advance, please excuse this newbie question. I am trying to build boost_1_48_0 and it is going well for all but 4 targets, two of which are the disclaimed <iostreams> failures relating to the bzip targets. However, I'm getting errors when trying to build : boost_1_48_0/libs/filesystem/v3/src/unique_path.cpp Here's the error (there's a nearly duplicate error for the statically linked target): gcc.compile.c++ /users/mpriest/Docs/Boost/build/boost/bin.v2/libs/filesystem/build/gcc-4.7.0/release/threading-multi/v3/src/unique_path.o libs/filesystem/v3/src/unique_path.cpp: In function 'void {anonymous}::system_crypt_random(void*, std::size_t, boost::system::error_code*)': libs/filesystem/v3/src/unique_path.cpp:68:49: error: 'read' was not declared in this scope libs/filesystem/v3/src/unique_path.cpp:71:17: error: 'close' was not declared in this scope libs/filesystem/v3/src/unique_path.cpp:79:13: error: 'close' was not declared in this scope "gcc" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -m64 -pthread -fPIC -DBOOST_ALL_NO_LIB=1 -DBOOST_FILESYSTEM_DYN_LINK=1 -DBOOST_SYSTEM_DYN_LINK=1 -DNDEBUG -I"." -c -o "/users/mpriest/Docs/Boost/build/boost/bin.v2/libs/filesystem/build/gcc-4.7.0/release/threading-multi/v3/src/unique_path.o" "libs/filesystem/v3/src/unique_path.cpp" ...failed gcc.compile.c++ /users/mpriest/Docs/Boost/build/boost/bin.v2/libs/filesystem/build/gcc-4.7.0/release/threading-multi/v3/src/unique_path.o... It seems like a simple include file availability issue or a pre-processor define issue, but I can't seem to affect a change in that compiler command through the user-config.jam file edits. When I run b2 with --debug-configuration option, I clearly see that change the -L and -I options in the user-config.jam file is reflected in the output, but still only see the -I"." option as shown above. It seems to me that those functions, read and close, should be made available through including the usual , and I think it's a bit curious that no other targets fail from the lack of "read" and "close". Any insight would be appreciated... thank you. Matt