diff --git a/flowexperimental/comp/wells/CompWellInterface.hpp b/flowexperimental/comp/wells/CompWellInterface.hpp
index de87bd6dd7..9efb70b0b6 100644
--- a/flowexperimental/comp/wells/CompWellInterface.hpp
+++ b/flowexperimental/comp/wells/CompWellInterface.hpp
@@ -43,7 +43,7 @@ public:
     using VectorBlockType = Dune::FieldVector<Scalar, Indices::numEq>;
     using BVector = Dune::BlockVector<VectorBlockType>;
     using CompConnectionData = PerforationData<Scalar>;
-    using SingleWellState = SingleCompWellState<FluidSystem, Scalar>;
+    using SingleWellState = SingleCompWellState<FluidSystem>;
 
     CompWellInterface(const Well& well,
                       const int index_of_well,
diff --git a/flowexperimental/comp/wells/CompWellModel.hpp b/flowexperimental/comp/wells/CompWellModel.hpp
index 92f7e0dbd8..d8348ae69f 100644
--- a/flowexperimental/comp/wells/CompWellModel.hpp
+++ b/flowexperimental/comp/wells/CompWellModel.hpp
@@ -143,7 +143,7 @@ private:
      const CompositionalConfig& comp_config_;
 
      // we will need two to handle the changes between time stepping
-     CompWellState<FluidSystem, Scalar> comp_well_states_;
+     CompWellState<FluidSystem> comp_well_states_;
 
      // this is needed for parallel running, not all the wells will be in the same process
      std::vector<Well> wells_ecl_;
diff --git a/flowexperimental/comp/wells/CompWellPrimaryVariables.hpp b/flowexperimental/comp/wells/CompWellPrimaryVariables.hpp
index c9cb8ae1a3..0598d69220 100644
--- a/flowexperimental/comp/wells/CompWellPrimaryVariables.hpp
+++ b/flowexperimental/comp/wells/CompWellPrimaryVariables.hpp
@@ -28,7 +28,7 @@
 
 namespace Opm {
 
-template <typename FluidSystem, typename Scalar>
+template <typename FluidSystem>
 class SingleCompWellState;
 
 template <typename FluidSystem, typename Indices>
@@ -56,7 +56,7 @@ public:
     using Eval = DenseAd::Evaluation<Scalar, numResEq>;
 
     using BVectorWell = typename CompWellEquations<Scalar, numWellEq, numResEq>::BVectorWell;
-    using SingleWellState = SingleCompWellState<FluidSystem, Scalar>;
+    using SingleWellState = SingleCompWellState<FluidSystem>;
 
     template <typename T>
     using FluidState = CompositionalFluidState<T, FluidSystem>;
diff --git a/flowexperimental/comp/wells/CompWellState.hpp b/flowexperimental/comp/wells/CompWellState.hpp
index 9b05aa03a3..bcd705ef8a 100644
--- a/flowexperimental/comp/wells/CompWellState.hpp
+++ b/flowexperimental/comp/wells/CompWellState.hpp
@@ -35,12 +35,13 @@
 
 namespace Opm {
 
-template <typename FluidSystem, typename Scalar>
+template <typename FluidSystem>
 class CompWellState
 {
 public:
+    using Scalar = typename FluidSystem::Scalar;
     using CompConnectionData = PerforationData<Scalar>;
-    using SingleWellState = SingleCompWellState<FluidSystem, Scalar>;
+    using SingleWellState = SingleCompWellState<FluidSystem>;
 
     explicit CompWellState(const CompositionalConfig& comp_config);
 
diff --git a/flowexperimental/comp/wells/CompWellState_impl.hpp b/flowexperimental/comp/wells/CompWellState_impl.hpp
index 8043ad4709..c2231c108e 100644
--- a/flowexperimental/comp/wells/CompWellState_impl.hpp
+++ b/flowexperimental/comp/wells/CompWellState_impl.hpp
@@ -19,16 +19,16 @@
 
 namespace Opm {
 
-template <typename FluidSystem, typename Scalar>
-CompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+CompWellState<FluidSystem>::
 CompWellState(const CompositionalConfig& comp_config)
     : comp_config_(comp_config)
 {
 }
 
 
-template <typename FluidSystem, typename Scalar>
-void CompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+void CompWellState<FluidSystem>::
 init(const std::vector<Well>& wells_ecl,
      const std::vector<Scalar>& cell_pressures,
      const Scalar temperature,
@@ -43,8 +43,8 @@ init(const std::vector<Well>& wells_ecl,
     // let us see how we gonna use it though
 }
 
-template <typename FluidSystem, typename Scalar>
-void CompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+void CompWellState<FluidSystem>::
 base_init(const std::vector<Well>& wells_ecl,
           const std::vector<Scalar>& cell_pressures,
           const Scalar temperature,
@@ -64,8 +64,8 @@ base_init(const std::vector<Well>& wells_ecl,
 
 }
 
-template <typename FluidSystem, typename Scalar>
-void CompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+void CompWellState<FluidSystem>::
 initSingleWell(const Well& well,
                const std::vector<Scalar>& cell_pressures,
                const Scalar tempearture,
@@ -81,8 +81,8 @@ initSingleWell(const Well& well,
 
 }
 
-template <typename FluidSystem, typename Scalar>
-void CompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+void CompWellState<FluidSystem>::
 initSingleInjector(const Well& well,
                    const std::vector<Scalar>& /* cell_pressures */,
                    const Scalar temperature,
@@ -98,8 +98,8 @@ initSingleInjector(const Well& well,
     ws.update_injector_targets(well, summary_state);
 }
 
-template <typename FluidSystem, typename Scalar>
-void CompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+void CompWellState<FluidSystem>::
 initSingleProducer(const Well& well,
                    const std::vector<Scalar>& /* cell_pressures */,
                    const Scalar temperature,
@@ -116,25 +116,25 @@ initSingleProducer(const Well& well,
     ws.update_producer_targets(well, cell_mole_fractions, summary_state);
 }
 
-template <typename FluidSystem, typename Scalar>
-const typename CompWellState<FluidSystem, Scalar>::SingleWellState&
-CompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+const typename CompWellState<FluidSystem>::SingleWellState&
+CompWellState<FluidSystem>::
 operator[](const std::string& well_name) const
 {
     return this->wells_[well_name];
 }
 
-template <typename FluidSystem, typename Scalar>
-typename CompWellState<FluidSystem, Scalar>::SingleWellState&
-CompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+typename CompWellState<FluidSystem>::SingleWellState&
+CompWellState<FluidSystem>::
 operator[](const std::string& well_name)
 {
     return this->wells_[well_name];
 }
 
-template <typename FluidSystem, typename Scalar>
+template <typename FluidSystem>
 data::Wells
-CompWellState<FluidSystem, Scalar>::
+CompWellState<FluidSystem>::
 report() const
 {
     if (this->wells_.empty()) {
diff --git a/flowexperimental/comp/wells/SingleCompWellState.hpp b/flowexperimental/comp/wells/SingleCompWellState.hpp
index faaacd3b35..093fceb84f 100644
--- a/flowexperimental/comp/wells/SingleCompWellState.hpp
+++ b/flowexperimental/comp/wells/SingleCompWellState.hpp
@@ -53,10 +53,12 @@ public:
     std::vector<std::size_t> ecl_index {};
 };
 
-template <typename FluidSystem, typename Scalar>
+template <typename FluidSystem>
 class SingleCompWellState
 {
 public:
+    using Scalar = typename FluidSystem::Scalar;
+
     SingleCompWellState(const std::string& name,
                         const CompositionalConfig& comp_config,
                         const Scalar temperature,
diff --git a/flowexperimental/comp/wells/SingleCompWellState_impl.hpp b/flowexperimental/comp/wells/SingleCompWellState_impl.hpp
index ac7cfcff20..7730500dca 100644
--- a/flowexperimental/comp/wells/SingleCompWellState_impl.hpp
+++ b/flowexperimental/comp/wells/SingleCompWellState_impl.hpp
@@ -49,8 +49,8 @@ CompConnectionData(const std::vector<PerforationData<Scalar>>& connections,
     }
 }
 
-template <typename FluidSystem, class Scalar>
-SingleCompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+SingleCompWellState<FluidSystem>::
 SingleCompWellState(const std::string& well_name,
                     const CompositionalConfig& comp_config,
                     const Scalar temperature_arg,
@@ -67,8 +67,8 @@ SingleCompWellState(const std::string& well_name,
 {
 }
 
-template <typename FluidSystem, class Scalar>
-void SingleCompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+void SingleCompWellState<FluidSystem>::
 update_injector_targets(const Well& well,
                         const SummaryState& st)
 {
@@ -113,8 +113,8 @@ update_injector_targets(const Well& well,
     }
 }
 
-template <typename FluidSystem, class Scalar>
-void SingleCompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+void SingleCompWellState<FluidSystem>::
 update_producer_targets(const Well& well,
                         const std::vector<std::vector<Scalar>>& cell_mole_fractions,
                         const SummaryState& st)
@@ -144,9 +144,9 @@ update_producer_targets(const Well& well,
     }
 }
 
-template <typename FluidSystem, class Scalar>
-Scalar
-SingleCompWellState<FluidSystem, Scalar>::
+template <typename FluidSystem>
+typename SingleCompWellState<FluidSystem>::Scalar
+SingleCompWellState<FluidSystem>::
 get_total_surface_rate() const
 {
     return std::accumulate(surface_phase_rates.begin(), surface_phase_rates.end(), Scalar(0));