OK so I've just been hit by my first Git SNAFU. 1) I checked out modular Boost as per https://svn.boost.org/trac/boost/wiki/TryModBoost 2) Changed libs/multiprecision to the develop branch also as per https://svn.boost.org/trac/boost/wiki/TryModBoost 3) Added some pending changes from the old SVN Trunk that I didn't commit before the changeover. 4) Ran the tests and everything failed, even though it was passing on SVN :-( The issue was that the headers under boost/ were now *copies* of the last release and no longer pointers to the new "develop" code. Interestingly some of the hard links were updated when I ran bjam, but apparently not all :-( Running bjam -a fixes the issue, but it's a very easy trap for the unwary.... John. PS, one other very annoying issue for VC++ users: 1) Open a test file. 2) Select a #included boost file, right click and select "Open document". 3) Document opens, but gives you a copy under boost/ not the "real" header under libs/mylib/. 4) Run away screaming after you've spent an XXX hours editing the wrong file....