[Boost-users] Warning while compiling asio UNDER_CE

I'm trying to compile my project with Asio support for Windows CE platform. I think, I don't need to define _WIN32_WINNT or _WIN32_WINDOWS but when compiling Asio headerI get this warning: "Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately. For example:..." I find this warning coded in "socket_types.hpp" file. I'm using Boost library 1.40.0. How can remove this warning message? Can I ignore it? Thanks. Carmelo