Hello, attached patch has just been committed to program_options/src/cmdline.cpp. It fixes the test failures observed on Tru64 for the cmdline_test test and probably applies to all 64 bit platforms. As a side note, there are many other incorrect uses of unsigned in this file which also should replaced by the correct size_type, but currently these uses don't cause a test failure. Markus Index: cmdline.cpp =================================================================== RCS file: /cvsroot/boost/boost/libs/program_options/src/cmdline.cpp,v retrieving revision 1.18 diff -u -r1.18 cmdline.cpp --- cmdline.cpp 6 May 2005 07:48:45 -0000 1.18 +++ cmdline.cpp 13 May 2005 11:21:38 -0000 @@ -351,7 +351,7 @@ { string name, adjacent; - unsigned p = tok.find('='); + string::size_type p = tok.find('='); if (p != tok.npos) { name = tok.substr(2, p-2);