diff --git a/opm/autodiff/NewtonSolver.hpp b/opm/autodiff/NewtonSolver.hpp
index afa019177..462d4e210 100644
--- a/opm/autodiff/NewtonSolver.hpp
+++ b/opm/autodiff/NewtonSolver.hpp
@@ -23,6 +23,7 @@
 
 #include <opm/autodiff/AutoDiffBlock.hpp>
 #include <opm/core/utility/parameters/ParameterGroup.hpp>
+#include <memory>
 
 namespace Opm {
 
@@ -64,13 +65,13 @@ namespace Opm {
 
         /// Construct solver for a given model.
         ///
-        /// The model is a std::shared_ptr because the object to which model points to is
+        /// The model is a std::unique_ptr because the object to which model points to is
         /// not allowed to be deleted as long as the NewtonSolver object exists.
         ///
         /// \param[in]      param   parameters controlling nonlinear Newton process
         /// \param[in, out] model   physical simulation model.
         explicit NewtonSolver(const SolverParameters& param,
-                              std::shared_ptr<PhysicalModel> model);
+                              std::unique_ptr<PhysicalModel> model);
 
         /// Take a single forward step, after which the states will be modified
         /// according to the physical model.
@@ -98,7 +99,7 @@ namespace Opm {
     private:
         // ---------  Data members  ---------
         SolverParameters param_;
-        std::shared_ptr<PhysicalModel> model_;
+        std::unique_ptr<PhysicalModel> model_;
         unsigned int newtonIterations_;
         unsigned int linearIterations_;
         unsigned int newtonIterationsLast_;
diff --git a/opm/autodiff/NewtonSolver_impl.hpp b/opm/autodiff/NewtonSolver_impl.hpp
index eda423d90..1e931b6ef 100644
--- a/opm/autodiff/NewtonSolver_impl.hpp
+++ b/opm/autodiff/NewtonSolver_impl.hpp
@@ -29,9 +29,9 @@ namespace Opm
 {
     template <class PhysicalModel>
     NewtonSolver<PhysicalModel>::NewtonSolver(const SolverParameters& param,
-                                              std::shared_ptr<PhysicalModel> model)
+                                              std::unique_ptr<PhysicalModel> model)
         : param_(param),
-          model_(model),
+          model_(std::move(model)),
           newtonIterations_(0),
           linearIterations_(0)
     {
diff --git a/opm/autodiff/SimulatorBase.hpp b/opm/autodiff/SimulatorBase.hpp
index 3be441c2d..ed99bf23e 100644
--- a/opm/autodiff/SimulatorBase.hpp
+++ b/opm/autodiff/SimulatorBase.hpp
@@ -151,7 +151,7 @@ namespace Opm
                                         WellState& well_state,
                                         const Wells* wells);
 
-        Solver* createSolver(const Wells* wells);
+        std::unique_ptr<Solver> createSolver(const Wells* wells);
 
         void
         computeRESV(const std::size_t               step,
diff --git a/opm/autodiff/SimulatorBase_impl.hpp b/opm/autodiff/SimulatorBase_impl.hpp
index 9c7755365..cbc1b9c26 100644
--- a/opm/autodiff/SimulatorBase_impl.hpp
+++ b/opm/autodiff/SimulatorBase_impl.hpp
@@ -330,7 +330,7 @@ namespace Opm
 
     template <class Implementation>
     auto SimulatorBase<Implementation>::createSolver(const Wells* wells)
-        -> Solver*
+        -> std::unique_ptr<Solver>
     {
         typedef typename Traits::Model Model;
         typedef typename Model::ModelParameters ModelParams;
@@ -354,7 +354,7 @@ namespace Opm
 
         typedef typename Solver::SolverParameters SolverParams;
         SolverParams solverParams( param_ );
-        return new Solver(solverParams, std::move(model));
+        return std::unique_ptr<Solver>(new Solver(solverParams, std::move(model)));
     }
 
     template <class Implementation>