diff --git a/src/reactmicp/solver/reactive_transport_solver.hpp b/src/reactmicp/solver/reactive_transport_solver.hpp
index ad21634..7af18ab 100644
--- a/src/reactmicp/solver/reactive_transport_solver.hpp
+++ b/src/reactmicp/solver/reactive_transport_solver.hpp
@@ -1,126 +1,126 @@
 #ifndef SPECMICP_REACTMICP_SOLVER_REACTIVETRANSPORTSOLVER_HPP
 #define SPECMICP_REACTMICP_SOLVER_REACTIVETRANSPORTSOLVER_HPP
 
 //! \file reactive_transport_solver.hpp The reactive transport solver
 
 //! \namespace specmicp::reactmicp::solver Namespace containing the algorithms for the reactive transport solver
 
 #include "common.hpp"
 #include <memory>
 #include "reactive_transport_solver_structs.hpp"
 
 #include "utils/options_handler.hpp"
 #include "utils/perfs_handler.hpp"
 
 // forward declarations
 // ====================
 namespace specmicp {
 namespace reactmicp {
 namespace solver {
 
 class VariablesBase;
 using VariablesBasePtr = std::shared_ptr<VariablesBase>;
 
 class TransportStaggerBase;
 class ChemistryStaggerBase;
 class UpscalingStaggerBase;
 using TransportStaggerPtr = std::shared_ptr<TransportStaggerBase>;
 using ChemistryStaggerPtr = std::shared_ptr<ChemistryStaggerBase>;
 using UpscalingStaggerPtr = std::shared_ptr<UpscalingStaggerBase>;
 
 namespace internal {
 struct ReactiveTransportResiduals;
 } // end namespace internal
 
 } // end namespace solver
 } // end namespace reactmicp
 } // end namespace specmicp
 
 
 // Reactive Transport Solver
 // =========================
 
 namespace specmicp {
 namespace reactmicp {
 namespace solver {
 
 //! \brief The reactive transport solver
 //!
 //! This class solves a reactive transport problem.
 //! The details of the problem are implemented in the staggers.
 //!
 //! There is three staggers :
 //!     - The transport stagger
 //!     - The chemistry stagger
 //!     - The upscaling stagger
 //!
 //! The transport stagger also implements the residuals used to checked the convergence.
 //!
 //! This algorithm do not update, modify the variables.
 //! The details must be implemented in the staggers.
 //! The variables shared by the algorithm is a shared_ptr to the abstract base class specmicp::reactmicp::solver::VariablesBase
 //! To be useful, this variable must be casted to the true class in the staggers.
 class ReactiveTransportSolver:
         public OptionsHandler<ReactiveTransportOptions>,
         public PerformanceHandler<ReactiveTransportPerformance>
 {
 public:
     //! \brief Build a reactive transport
     //!
     //! \param transport_stagger shared_ptr to a transport stagger
     //! \param chemistry_stagger shared_ptr to a chemistry stagger
     //! \param upscaling_stagger shared_ptr to an upscaling stagger
     ReactiveTransportSolver(
             TransportStaggerPtr transport_stagger,
             ChemistryStaggerPtr chemistry_stagger,
             UpscalingStaggerPtr upscaling_stagger
             ):
         m_transport_stagger(transport_stagger),
         m_chemistry_stagger(chemistry_stagger),
         m_upscaling_stagger(upscaling_stagger)
     {}
 
     //! \brief Solve a timestep
     //!
     //! \param timestep The duration of the timestep
     //! \param variables shared_ptr to the variables
     ReactiveTransportReturnCode solve_timestep(
             scalar_t timestep,
             VariablesBasePtr variables
             );
 
     //! \brief Return the timer
-    ReactiveTransportTimer get_timer() {return m_timer;}
+    ReactiveTransportTimer& get_timer() {return m_timer;}
 
 private: // members
     //! \brief One iteration inside the timestep
     //!
     //! \param variables shared_ptr to the variables
     //! \param residuals struct containing the residuals information
     ReactiveTransportReturnCode one_iteration(
             VariablesBasePtr variables,
             internal::ReactiveTransportResiduals& residuals
             );
     //! \brief Check the convergence
     //!
     //! \param variables shared_ptr to the variables
     //! \param residuals struct containing the residuals information
     ReactiveTransportReturnCode check_convergence(
             VariablesBasePtr variables,
             const internal::ReactiveTransportResiduals& residuals,
             bool bypass
             );
 
 private: // attributes
     TransportStaggerPtr m_transport_stagger; //!< The transport stagger
     ChemistryStaggerPtr m_chemistry_stagger; //!< The chemistry stagger
     UpscalingStaggerPtr m_upscaling_stagger; //!< The upscaling stagger
 
     ReactiveTransportTimer m_timer;
 };
 
 } // end namespace solver
 } // end namespace reactmicp
 } // end namespace specmicp
 
 #endif // SPECMICP_REACTMICP_SOLVER_REACTIVETRANSPORTSOLVER_HPP