diff --git a/include/hpp/manipulation/problem-solver.hh b/include/hpp/manipulation/problem-solver.hh
index 691833bfe0fc411c94de4785f921c33aa165e465..07608832919b6e9da1b5de3eef236d3d2a3d07fc 100644
--- a/include/hpp/manipulation/problem-solver.hh
+++ b/include/hpp/manipulation/problem-solver.hh
@@ -153,7 +153,7 @@ namespace hpp {
       virtual void resetProblem ();
 
       /// Get pointer to problem
-      ProblemPtr_t problem ()
+      ProblemPtr_t problem () const
       {
 	return problem_;
       }