There's a problem in 1.37 as it stands in that: * If Boost.TR1 is in the include path, and, * A Boost header is included that includes <cmath>. Then the TR1 version of <cmath> gets included. This is relatively harmless on *nix platforms - except for somewhat longer compile times - but for windows compilers that support auto-linking then the headers want to link to the math TR1 libraries even if the user is actually using a header only library like spirit for example. This is the subject of bug report: http://svn.boost.org/trac/boost/ticket/2392. There is a trivial fix, which is to replace #includes of <cmath> with <boost/config/no_tr1/cmath.hpp>: I've just applied this to Trunk (so you know who to blame if this causes any issues!), but should this be applied to the release branch as well? Changeset here: http://svn.boost.org/trac/boost/changeset/49254/trunk Regards, John.