diff --git a/include/core/matrix_free_operator.h b/include/core/matrix_free_operator.h
index 113915d4..0f2e5dc7 100644
--- a/include/core/matrix_free_operator.h
+++ b/include/core/matrix_free_operator.h
@@ -49,9 +49,9 @@ class matrixFreeOperator
 
 protected:
   /**
-   * \brief User-implemented PDE. TODO
+   * \brief User-implemented PDE.
    */
-  void
+  virtual void
   nonexplicit_RHS(variableContainer<dim, degree, number>    &variable_list,
                   const Point<dim, VectorizedArray<number>> &q_point_loc) const;
 
diff --git a/include/core/temp_test.h b/include/core/temp_test.h
index a677df4d..d0d87949 100644
--- a/include/core/temp_test.h
+++ b/include/core/temp_test.h
@@ -30,11 +30,10 @@
 
 #include <core/conditional_ostreams.h>
 #include <core/matrix_free_operator.h>
-#include <fstream>
 #include <iostream>
 
-const unsigned int degree_finite_element = 2;
-const unsigned int dimension             = 3;
+const unsigned int degree    = 2;
+const unsigned int dimension = 3;
 
 template <int dim>
 class LaplaceProblem
@@ -62,11 +61,11 @@ class LaplaceProblem
   MappingQ1<dim> mapping;
 
   AffineConstraints<double> constraints;
-  using SystemMatrixType = matrixFreeOperator<dim, degree_finite_element, double>;
+  using SystemMatrixType = matrixFreeOperator<dim, degree, double>;
   SystemMatrixType system_matrix;
 
   MGConstrainedDoFs mg_constrained_dofs;
-  using LevelMatrixType = matrixFreeOperator<dim, degree_finite_element, float>;
+  using LevelMatrixType = matrixFreeOperator<dim, degree, float>;
   MGLevelObject<LevelMatrixType> mg_matrices;
 
   LinearAlgebra::distributed::Vector<double> solution;
@@ -81,7 +80,7 @@ LaplaceProblem<dim>::LaplaceProblem()
       MPI_COMM_WORLD,
       Triangulation<dim>::limit_level_difference_at_vertices,
       parallel::distributed::Triangulation<dim>::construct_multigrid_hierarchy)
-  , fe(degree_finite_element)
+  , fe(degree)
   , dof_handler(triangulation)
 {}
 
@@ -194,7 +193,7 @@ LaplaceProblem<dim>::assemble_rhs()
   Timer time;
 
   system_rhs = 0;
-  FEEvaluation<dim, degree_finite_element> phi(*system_matrix.get_matrix_free());
+  FEEvaluation<dim, degree> phi(*system_matrix.get_matrix_free());
   for (unsigned int cell = 0; cell < system_matrix.get_matrix_free()->n_cell_batches();
        ++cell)
     {