Hi, There is a warning in Boost.Config under CYGWIN that appears to much times as the config files is used a lot. gcc.compile.c++ bin.v2/libs/wave/build/gcc-4.3.4/release/link-static/threading-m ulti/wave_config_constant.o In file included from ./boost/config.hpp:53,                  from ./boost/wave/wave_config.hpp:16,                  from libs\wave\src\wave_config_constant.cpp:20: ./boost/config/platform/cygwin.hpp:10:1: warning: "BOOST_CYGWIN" redefined In file included from ./boost/config.hpp:35,                  from ./boost/wave/wave_config.hpp:16,                  from libs\wave\src\wave_config_constant.cpp:20: ./boost/config/compiler/gcc.hpp:96:1: warning: this is the location of the previ ous definition John, I have attached a patch. for the trunk. Could it be include? Best, Vicente