diff --git a/SolverGodunovFiveEq.cpp b/SolverGodunovFiveEq.cpp
index 2e72186..29c5122 100644
--- a/SolverGodunovFiveEq.cpp
+++ b/SolverGodunovFiveEq.cpp
@@ -987,7 +987,7 @@ SolverGodunovFiveEq<dim, device_t>::save_solution_hdf5([[maybe_unused]] bool pur
 template <size_t dim, typename device_t>
 void
 SolverGodunovFiveEq<dim, device_t>::synchronize_mpi_ghost_data(
-  [[maybe_unused]] DataArrayBlock_t data)
+  [[maybe_unused]] DataArrayBlock_t const & data)
 {
 
 #ifdef KALYPSSO_CORE_USE_MPI
@@ -1004,7 +1004,7 @@ SolverGodunovFiveEq<dim, device_t>::synchronize_mpi_ghost_data(
 // =======================================================
 template <size_t dim, typename device_t>
 void
-SolverGodunovFiveEq<dim, device_t>::fill_outside_quadrants(DataArrayBlock_t data)
+SolverGodunovFiveEq<dim, device_t>::fill_outside_quadrants(DataArrayBlock_t const & data)
 {
 
   // assert data has expected size (in terms of number of octants/quadrants)
diff --git a/SolverGodunovFiveEq.h b/SolverGodunovFiveEq.h
index b450cc1..37553a1 100644
--- a/SolverGodunovFiveEq.h
+++ b/SolverGodunovFiveEq.h
@@ -419,7 +419,7 @@ class SolverGodunovFiveEq : public kalypsso::SolverBase
   //! synchronize MPI ghost data / only necessary when MPI is activated
   //! this will also do external border only when mesh is periodic
   void
-  synchronize_mpi_ghost_data(DataArrayBlock_t data);
+  synchronize_mpi_ghost_data(DataArrayBlock_t const & data);
 
   //! when mesh is not periodic, the number of outside quadrants is not zero, so we need to fill
   //! outside quadrant user data according to the border condition. This is where we apply border
@@ -428,7 +428,7 @@ class SolverGodunovFiveEq : public kalypsso::SolverBase
   //! Just to be clear, let's repeat that array m_U must be sized upon the total number of
   //! octants (owned, ghost and outside).
   void
-  fill_outside_quadrants(DataArrayBlock_t data);
+  fill_outside_quadrants(DataArrayBlock_t const & data);
 
   //! mark cells for refinement
   void