With 1.48 on 64-bit Windows 7 and gcc 4.6.0, the following code fails to compile with -std=c++0x: #include int main(){} The diagnostics are: C:\Users\Scott\Libraries\Boost\Current/boost/lexical_cast.hpp: In member function 'bool boost::detail::lexical_stream_limited_src::shl_float(float, wchar_t*)': C:\Users\Scott\Libraries\Boost\Current/boost/lexical_cast.hpp:1210:120: error: there are no arguments to 'swprintf' that depend on a template parameter, so a declaration of 'swprintf' must be available [-fpermissive] C:\Users\Scott\Libraries\Boost\Current/boost/lexical_cast.hpp:1210:120: note: (if you use '-fpermissive', G++ will accept your code, but allowing the use of an undeclared name is deprecated) C:\Users\Scott\Libraries\Boost\Current/boost/lexical_cast.hpp: In member function 'bool boost::detail::lexical_stream_limited_src::shl_double(double, wchar_t*)': C:\Users\Scott\Libraries\Boost\Current/boost/lexical_cast.hpp:1231:122: error: there are no arguments to 'swprintf' that depend on a template parameter, so a declaration of 'swprintf' must be available [-fpermissive] The code compiles fine without -std=c++0x. I don't recall having this problem with earlier releases. Pilot error or library implementation problem? Thanks, Scott