Hi, This concerns Boost 1.33.1. In order to build some code I have that uses the Graph package, I had to make a change to `boost/graph/graph_traits.hpp'. Near the bottom of that file a namespace kludge is conditionalized by #if defined(__GNUC__) && defined(__SGI_STL_PORT) This kludge breaks (and, as far as I can tell, is no longer necessary) under GCC 4 (I presume; I've only actually tried 4.1.1). So I changed the above line to #if defined(__GNUC__) && __GNUC__ < 4 && defined(__SGI_STL_PORT) This seems to work fine for me. -- Scott