Index: boost/thread/future.hpp
===================================================================
--- boost/thread/future.hpp	(revision 59418)
+++ boost/thread/future.hpp	(working copy)
@@ -412,7 +412,7 @@
                 {
                     for(unsigned i=0;i<count;++i)
                     {
-                        locks[i]=boost::unique_lock<boost::mutex>(futures[i].future->mutex);
+                        locks[i].swap(boost::unique_lock<boost::mutex>(futures[i].future->mutex));
                     }
                 }