(Long-time reader, first-time poster) Hi all Recently I wanted to upgrade from 1.33 and got build errors in boost format. It is a quite large codebase which, for legacy reasons, has to be built with 1-byte structure alignment (this cannot easily be changed). The error comes from an boost::optional<boost::io::detail::locale_t> in boost/format/internal.hpp that wants to be 4-byte aligned (platform is Win32 vc9). Now I cannot just include this (or all) boost headers with 4- (or 8-)byte alignment because they include other std headers which have already been included before (with 1-byte alignment). Is there an easy solution to this that I am missing despite changing all includes? Is there information on such interdependencies somewhere? Or do I have to bite the bullet and include all standard headers with a suitable alignment. I am sorry if this has been discussed before, but I could not find anything. Thanks, Christoph.