Hi, I've found that when using Boost on Visual Studio 2005, I get warning C4103 when including any boost header which end up including abi_{prefix,suffix}.hpp (eg. iostreams/filter/zlib.hpp) or which manually performs a #include BOOST_ABI_{PREFIX,SUFFIX} (eg. regex/v4/regex_traits_defaults.hpp). An explanation for the warning can be found here: http://windowssdk.msdn.microsoft.com/en-us/library/t4d0762d.aspx What is happening is that config/abi/msvc_{prefix,suffix}.hpp performs "#pragma pack(push,8)" (in msvc_prefix.hpp) and then performs a "#pragma pack(pop)" (in msvc_suffix.hpp). This leads the compiler to think that the packing alignment has erroneously changed, generating unnecessary warnings. Could something be done to fix this? I think the warning needs to be disabled prior to including BOOST_ABI_{PREFIX,SUFFIX}. Thanks, -Edward