Hello, I've attached a patch to allow the program_options library to build on Sun's C++ compiler. Cheers, Chris Bond diff -ru boost_1_33_1/libs/program_options/src/options_description.cpp boost/libs/program_options/src/options_description.cpp --- boost_1_33_1/libs/program_options/src/options_description.cpp Wed Jul 13 09:32:40 2005 +++ boost/libs/program_options/src/options_description.cpp Thu Mar 30 18:35:19 2006 @@ -384,7 +384,7 @@ { // is last_space within the second half ot the // current line - if (unsigned(distance(last_space, line_end)) < + if (static_cast<unsigned int>(distance(last_space, line_end)) < (line_length - indent) / 2) { line_end = last_space;