diff --git a/include/hpp/manipulation/graph/statistics.hh b/include/hpp/manipulation/graph/statistics.hh
index 27ff91bc5f12ad0a3bd6b480203eac53d6b786ac..6c3a8ba781f4abadb7604805459caf27e7623c4b 100644
--- a/include/hpp/manipulation/graph/statistics.hh
+++ b/include/hpp/manipulation/graph/statistics.hh
@@ -84,7 +84,7 @@ namespace hpp {
           std::ostream& print (std::ostream& os) const;
 
         private:
-          StateWkPtr_t state_;
+          StatePtr_t state_;
 
           typedef std::list <RoadmapNodePtr_t> RoadmapNodes_t;
           RoadmapNodes_t roadmapNodes_;
@@ -195,7 +195,7 @@ namespace hpp {
 
         private:
           /// The constraint graph
-          graph::GraphWkPtr_t graph_;
+          graph::GraphPtr_t graph_;
       };
       typedef StateHistogram NodeHistogram HPP_MANIPULATION_DEPRECATED;
       typedef boost::shared_ptr <StateHistogram> NodeHistogramPtr_t;
diff --git a/include/hpp/manipulation/roadmap-node.hh b/include/hpp/manipulation/roadmap-node.hh
index e4de416f258bdd85232d60975ff50da554cc049b..439677d58b9343d5fd39a278f58c6981e61070e3 100644
--- a/include/hpp/manipulation/roadmap-node.hh
+++ b/include/hpp/manipulation/roadmap-node.hh
@@ -99,14 +99,14 @@ namespace hpp {
 
         SymbolicComponentPtr_t symbolicComponent () const
         {
-          return symbolicCC_.lock();
+          return symbolicCC_;
         }
 
       private:
         CachingSystem cacheSystem_;
 
         graph::StateWkPtr_t state_;
-        SymbolicComponentWkPtr_t symbolicCC_;
+        SymbolicComponentPtr_t symbolicCC_;
     };
   } // namespace manipulation
 } // namespace hpp
diff --git a/src/graph/statistics.cc b/src/graph/statistics.cc
index fec9efab49ad158eaa76cf207fcaa1618d7957b4..0012c15fe9bd7177c8cdd1246a3aadbebbbc32c0 100644
--- a/src/graph/statistics.cc
+++ b/src/graph/statistics.cc
@@ -119,7 +119,7 @@ namespace hpp {
 
       const StatePtr_t& NodeBin::state () const
       {
-        return state_.lock();
+        return state_;
       }
 
       std::ostream& NodeBin::print (std::ostream& os) const
@@ -213,7 +213,7 @@ namespace hpp {
 
       const graph::GraphPtr_t& StateHistogram::constraintGraph () const
       {
-        return graph_.lock();
+        return graph_;
       }
 
       HistogramPtr_t StateHistogram::clone () const