I get the following error message when running my Python module after building everything (but Python) with gcc 3.4.0... ImportError: /lib/libgcc_s.so.1: version `GCC_3.3' not found (required by /usr/local/lib/libstdc++.so.6) Running the same C++ code with a main program, i.e. not via Python/boost, there's no problem. Any clues? Some things I've tried... There's a libgcc_s.so.1 installed in /usr/local/lib. So I try setting LD_LIBRARY_PATH (which I don't normally set) to /usr/local/lib. Then running my program from Python via Boost crashes initializing the first basic_string. Or, in another variation of my program in initiaizing an ifstream with the debugger looking for ../../../../gcc-3.3.3/stdc++v3/ios.cc This source file is not on my machine, so it seems to say I'm linking against a library in /usr/lib which is incompatible with my build of gcc in /usr/local/lib.