Index: reverse_lock.hpp
===================================================================
--- reverse_lock.hpp	(revision 82281)
+++ reverse_lock.hpp	(working copy)
@@ -30,12 +30,22 @@
             }
             mtx=m.release();
         }
+
+        /** Re-take lock. Must be done before destruction. 
+            Note that this cannot be done in the destructor, since locking might throw. */
+        void lock()
+        {
+            if (mtx) {
+                mutex_type * mtx_tmp = mtx;
+                mtx = 0; // prevent destructor assert from also failing in the event of lock failure
+                mtx_tmp->lock();
+                m = BOOST_THREAD_MAKE_RV_REF(Lock(*mtx_tmp, adopt_lock));
+            }
+        }
+
         ~reverse_lock()
         {
-          if (mtx) {
-            mtx->lock();
-            m = BOOST_THREAD_MAKE_RV_REF(Lock(*mtx, adopt_lock));
-          }
+            BOOST_VERIFY(mtx == 0); // check that lock has been explicitly called
         }
 
     private: