diff --git a/ProcessLib/ProcessVariable.cpp b/ProcessLib/ProcessVariable.cpp
index 00c28840f802ecbace57979991728c4070b9cb7d..d6466c910437678d22a1c013d7a191e6c7ff16f7 100644
--- a/ProcessLib/ProcessVariable.cpp
+++ b/ProcessLib/ProcessVariable.cpp
@@ -98,6 +98,7 @@ ProcessVariable::ProcessVariable(BaseLib::ConfigTree const& config,
 ProcessVariable::ProcessVariable(ProcessVariable&& other)
     : _name(std::move(other._name)),
       _mesh(other._mesh),
+      _n_components(other._n_components),
       _initial_condition(std::move(other._initial_condition)),
       _dirichlet_bc_configs(std::move(other._dirichlet_bc_configs)),
       _neumann_bc_configs(std::move(other._neumann_bc_configs))
diff --git a/ProcessLib/ProcessVariable.h b/ProcessLib/ProcessVariable.h
index d2b8d4b9796bdde8c54c7a11a23328857e31da01..9b49733ebcc2c0b887dc1ff1b274038342163ec4 100644
--- a/ProcessLib/ProcessVariable.h
+++ b/ProcessLib/ProcessVariable.h
@@ -104,7 +104,7 @@ public:
 private:
 	std::string const _name;
 	MeshLib::Mesh& _mesh;
-	int _n_components;
+	const int _n_components;
 	std::unique_ptr<InitialCondition> _initial_condition;
 	std::vector<std::unique_ptr<UniformDirichletBoundaryCondition>>
 	    _dirichlet_bc_configs;