diff --git a/src/pyhpp/manipulation/problem.cc b/src/pyhpp/manipulation/problem.cc
index 3058204..498daf7 100644
--- a/src/pyhpp/manipulation/problem.cc
+++ b/src/pyhpp/manipulation/problem.cc
@@ -55,13 +55,10 @@ Problem::Problem(const hpp::manipulation::ProblemPtr_t& object)
 
 void Problem::constraintGraph(const PyWGraphPtr_t& graph) {
   asManipulationProblem()->constraintGraph(graph->obj);
+  graph_ = graph;
 }
 
-PyWGraphPtr_t Problem::constraintGraph() const {
-  pyhpp::manipulation::PyWGraph* graph =
-      new PyWGraph(asManipulationProblem()->constraintGraph());
-  return std::shared_ptr<PyWGraph>(graph);
-}
+PyWGraphPtr_t Problem::constraintGraph() const { return graph_; }
 
 void Problem::checkProblem() const { asManipulationProblem()->checkProblem(); }
 
diff --git a/src/pyhpp/manipulation/problem.hh b/src/pyhpp/manipulation/problem.hh
index ae8df70..e04c165 100644
--- a/src/pyhpp/manipulation/problem.hh
+++ b/src/pyhpp/manipulation/problem.hh
@@ -49,6 +49,7 @@ namespace manipulation {
 // Wrapper class for hpp::manipulation::Problem
 struct Problem : public pyhpp::core::Problem {
   hpp::core::Container<JointAndShapes_t> jointAndShapes;
+  PyWGraphPtr_t graph_;
 
   Problem(const PyWDevicePtr_t& robot);
   Problem(const hpp::manipulation::ProblemPtr_t& object);