I have tested the following example code with Boost 1.61. And it worked (ignore the potential race conditions when accessing the variable 'p'). But I am not sure the fiber promise can be used in this way or I am just being lucky. #include <cstdlib> #include "boost/fiber/fiber.hpp" #include "boost/fiber/future.hpp" #include "boost/thread.hpp" #include <set> #include <iostream> #include <boost/date_time/posix_time/posix_time_duration.hpp> #include <boost/thread/pthread/mutex.hpp> #include <boost/thread/lock_guard.hpp> #include "boost/thread/pthread/thread_data.hpp" #include "boost/chrono/duration.hpp" using namespace std; boost::fibers::promise<int>* p; void wait() { p = new boost::fibers::promise<int>; auto future = p->get_future(); auto status = future.wait(); std::cout << "Value: " << future.get() << std::endl; delete p; } void f() { boost::fibers::fiber fiberJob(&wait); fiberJob.join(); } void setf() { // Is it safe to do this? boost::this_thread::sleep(boost::posix_time::seconds(5)); p->set_value(20); } void f1() { boost::fibers::fiber fiberJob(&setf); fiberJob.join(); } int main(int argc, char** argv) { boost::thread t(&f); setf(); cout << "Here" << endl; t.join(); cout << "Here 2" << endl; return 0; }