Hi, I've noticed that on Windows using call_once is not thread-safe as the once_flag structure has a destructor which makes it dynamically initialized. I can see the ticket [1] for this problem is hanging for quite a while, whereas the bug is quite critical, IMHO. Are there any plans on fixing it, perhaps by reverting the change that introduced it? [1] <https://svn.boost.org/trac/boost/ticket/4225> PS: Curiously, the change was made on April, 1st. A long-term joke? :)