--- lock_types.hpp~	2016-11-21 21:29:59.000000000 -0200
+++ lock_types.hpp	2016-11-22 18:58:55.056399210 -0200
@@ -445,10 +445,15 @@ namespace boost
       }
       if (!owns_lock())
       {
+#if defined BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED
         boost::throw_exception(
             boost::lock_error(static_cast<int>(system::errc::operation_not_permitted), "boost unique_lock doesn't own the mutex"));
+#endif
+      }
+       else
+      {
+        m->unlock();
       }
-      m->unlock();
       is_locked = false;
     }