diff --git a/src/TNL/Problems/HeatEquationProblem.h b/src/TNL/Problems/HeatEquationProblem.h
index 94bc122fdbb74b4b1cdc7ae8d1d1abac33f293ca..b86aa02f8d06e3a4a4c9ecc13ef02127062608dd 100644
--- a/src/TNL/Problems/HeatEquationProblem.h
+++ b/src/TNL/Problems/HeatEquationProblem.h
@@ -32,9 +32,9 @@ template< typename Mesh,
           typename DifferentialOperator = Operators::LinearDiffusion< Mesh,
                                                               typename BoundaryCondition::RealType > >
 class HeatEquationProblem : public PDEProblem< Mesh,
-                                                     typename DifferentialOperator::RealType,
-                                                     typename Mesh::DeviceType,
-                                                     typename DifferentialOperator::IndexType  >
+                                               typename DifferentialOperator::RealType,
+                                               typename Mesh::DeviceType,
+                                               typename DifferentialOperator::IndexType  >
 {
    public: