diff --git a/src/TNL/Problems/HeatEquationProblem.h b/src/TNL/Problems/HeatEquationProblem.h
index 94bc122fdbb74b4b1cdc7ae8d1d1abac33f293ca..33046f58cc847a3654057da2150504ef77447de5 100644
--- a/src/TNL/Problems/HeatEquationProblem.h
+++ b/src/TNL/Problems/HeatEquationProblem.h
@@ -44,7 +44,7 @@ class HeatEquationProblem : public PDEProblem< Mesh,
       typedef Functions::MeshFunction< Mesh > MeshFunctionType;
       typedef SharedPointer< MeshFunctionType, DeviceType > MeshFunctionPointer;
       typedef PDEProblem< Mesh, RealType, DeviceType, IndexType > BaseType;
-      typedef Matrices::CSR< RealType, DeviceType, IndexType > MatrixType;
+      typedef Matrices::SlicedEllpack< RealType, DeviceType, IndexType > MatrixType;
       typedef SharedPointer< DifferentialOperator > DifferentialOperatorPointer;
       typedef SharedPointer< BoundaryCondition > BoundaryConditionPointer;
       typedef SharedPointer< RightHandSide, DeviceType > RightHandSidePointer;
diff --git a/src/TNL/Problems/PDEProblem.h b/src/TNL/Problems/PDEProblem.h
index 612e325e3771ec2560c955fe3ff64a98e19f3920..431f6588828d2166f42bbc297eb533ee00dd260c 100644
--- a/src/TNL/Problems/PDEProblem.h
+++ b/src/TNL/Problems/PDEProblem.h
@@ -12,7 +12,7 @@
 
 #include <TNL/Problems/Problem.h>
 #include <TNL/SharedPointer.h>
-#include <TNL/Matrices/CSR.h>
+#include <TNL/Matrices/SlicedEllpack.h>
 
 namespace TNL {
 namespace Problems {
@@ -34,7 +34,7 @@ class PDEProblem : public Problem< Real, Device, Index >
       typedef SharedPointer< MeshType, DeviceType > MeshPointer;
       typedef Containers::Vector< RealType, DeviceType, IndexType> DofVectorType;
       typedef SharedPointer< DofVectorType, DeviceType > DofVectorPointer;
-      typedef Matrices::CSR< RealType, DeviceType, IndexType > MatrixType;
+      typedef Matrices::SlicedEllpack< RealType, DeviceType, IndexType > MatrixType;
       typedef Containers::Vector< RealType, DeviceType, IndexType > MeshDependentDataType;
       typedef SharedPointer< MeshDependentDataType, DeviceType > MeshDependentDataPointer;