Index: boost/config/stdlib/libstdcpp3.hpp

===================================================================

--- boost/config/stdlib/libstdcpp3.hpp.orig     2012-01-14 19:15:34.957877838 +0100

+++ boost/config/stdlib/libstdcpp3.hpp  2012-01-14 19:19:09.660901373 +0100

@@ -34,7 +34,8 @@

 #ifdef __GLIBCXX__ // gcc 3.4 and greater:

 #  if defined(_GLIBCXX_HAVE_GTHR_DEFAULT) \

         || defined(_GLIBCXX__PTHREADS) \

-        || defined(_GLIBCXX_HAS_GTHREADS)

+        || defined(_GLIBCXX_HAS_GTHREADS) \

+        || defined(_WIN32)

       //

       // If the std lib has thread support turned on, then turn it on in Boost

       // as well.  We do this because some gcc-3.4 std lib headers define _REENTANT