--- /usr/include/boost/xpressive/detail/utility/tracking_ptr.hpp	2007-07-03 11:35:38.000000000 -0400
+++ boost/xpressive/detail/utility/tracking_ptr.hpp	2007-09-03 19:48:09.000000000 -0400
@@ -203,7 +203,8 @@
     }
 
     enable_reference_tracking(enable_reference_tracking<Derived> const &that)
-      : refs_()
+      : enable_shared_from_this<Derived>()
+      , refs_()
       , deps_()
     {
         this->operator =(that);