Hello, I build my project under Cygwin, and get errors like this: .../boost/asio/detail/socket_types.hpp:125: error: 'INET_ADDRSTRLEN' was not declared in this scope I see that INET_ADDRSTRLEN is defined in /usr/include/cygwin/in.h , but asio doesn't include it. Besides, there're some more undefined macros, which are defined in /usr/include/cygwin/in6.h Meanwhile I apply an ad-hoc solution, but I'm wondering if someone else encountered this issue and what would be the right solution. Thanks.