diff --git a/BaseLib/RunTime.h b/BaseLib/RunTime.h
index 532f8ee8a71fe2b297d38368473ff176d9d8fdc2..2d7111f50f09415ac91793655ed495777468429e 100644
--- a/BaseLib/RunTime.h
+++ b/BaseLib/RunTime.h
@@ -14,7 +14,7 @@
 
 #pragma once
 
-#ifdef USE_MPI
+#ifdef USE_PETSC
 #include <mpi.h>
 #else
 #include <chrono>
@@ -22,38 +22,37 @@
 
 namespace BaseLib
 {
-
 /// Count the running time.
 class RunTime
 {
-    public:
-        /// Start the timer.
-        void start()
-        {
-#ifdef USE_MPI
-            _start_time = MPI_Wtime();
+public:
+    /// Start the timer.
+    void start()
+    {
+#ifdef USE_PETSC
+        _start_time = MPI_Wtime();
 #else
-            _start_time = std::chrono::system_clock::now();
+        _start_time = std::chrono::system_clock::now();
 #endif
-        }
+    }
 
-        /// Get the elapsed time in seconds.
-        double elapsed() const
-        {
-#ifdef USE_MPI
-            return MPI_Wtime() - _start_time;
+    /// Get the elapsed time in seconds.
+    double elapsed() const
+    {
+#ifdef USE_PETSC
+        return MPI_Wtime() - _start_time;
 #else
-            using namespace std::chrono;
-            return duration<double>(system_clock::now() - _start_time).count();
+        using namespace std::chrono;
+        return duration<double>(system_clock::now() - _start_time).count();
 #endif
-        }
+    }
 
-    private:
-#ifdef USE_MPI
-        double _start_time = std::numeric_limits<double>::quiet_NaN();
+private:
+#ifdef USE_PETSC
+    double _start_time = std::numeric_limits<double>::quiet_NaN();
 #else
-        std::chrono::time_point<std::chrono::system_clock> _start_time;
+    std::chrono::time_point<std::chrono::system_clock> _start_time;
 #endif
 };
 
-} // end namespace BaseLib
+}  // end namespace BaseLib
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9192a1bf8ae50c054ad7ab5cb1d6ae6f220c0c82..5edeec9c06e9deae09ee1ffc9b437214f53192cd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -194,10 +194,6 @@ if(OGS_USE_MKL)
     include_directories(SYSTEM ${MKL_INCLUDE_DIR})
 endif()
 
-if(OGS_USE_MPI)
-    add_definitions(-DUSE_MPI)
-endif()
-
 # Eigen
 if(CMAKE_BUILD_TYPE STREQUAL "Debug")
     add_definitions(-DEIGEN_INITIALIZE_MATRICES_BY_NAN)
diff --git a/MeshLib/IO/VtkIO/VtuInterface.cpp b/MeshLib/IO/VtkIO/VtuInterface.cpp
index 8c7b2054168d40798df8bac6ad7695fbbe0d875a..0cc6473c5bdc4f045b915b4e56d192a588875e3f 100644
--- a/MeshLib/IO/VtkIO/VtuInterface.cpp
+++ b/MeshLib/IO/VtkIO/VtuInterface.cpp
@@ -13,20 +13,20 @@
 
 #include "VtuInterface.h"
 
-#include <vtkNew.h>
 #include <vtkGenericDataObjectReader.h>
+#include <vtkNew.h>
 #include <vtkXMLUnstructuredGridReader.h>
 #include <vtkXMLUnstructuredGridWriter.h>
-#if defined(USE_PETSC) || defined(USE_MPI)
+#if defined(USE_PETSC)
 #include <vtkXMLPUnstructuredGridWriter.h>
 #endif
 #include <vtkSmartPointer.h>
 #include <vtkUnstructuredGrid.h>
 
-#include "BaseLib/Logging.h"
-
 #include <boost/algorithm/string/erase.hpp>
 
+#include "BaseLib/Logging.h"
+
 #ifdef USE_PETSC
 #include <petsc.h>
 #endif
@@ -40,9 +40,9 @@ namespace MeshLib
 {
 namespace IO
 {
-
-VtuInterface::VtuInterface(const MeshLib::Mesh* mesh, int dataMode, bool compress) :
-    _mesh(mesh), _data_mode(dataMode), _use_compressor(compress)
+VtuInterface::VtuInterface(const MeshLib::Mesh* mesh, int dataMode,
+                           bool compress)
+    : _mesh(mesh), _data_mode(dataMode), _use_compressor(compress)
 {
     if (_data_mode == vtkXMLWriter::Ascii && compress)
     {
@@ -50,9 +50,10 @@ VtuInterface::VtuInterface(const MeshLib::Mesh* mesh, int dataMode, bool compres
     }
 }
 
-MeshLib::Mesh* VtuInterface::readVTUFile(std::string const &file_name)
+MeshLib::Mesh* VtuInterface::readVTUFile(std::string const& file_name)
 {
-    if (!BaseLib::IsFileExisting(file_name)) {
+    if (!BaseLib::IsFileExisting(file_name))
+    {
         ERR("File '{:s}' does not exist.", file_name);
         return nullptr;
     }
@@ -69,8 +70,10 @@ MeshLib::Mesh* VtuInterface::readVTUFile(std::string const &file_name)
         return nullptr;
     }
 
-    std::string const mesh_name (BaseLib::extractBaseNameWithoutExtension(file_name));
-    return MeshLib::VtkMeshConverter::convertUnstructuredGrid(vtkGrid, mesh_name);
+    std::string const mesh_name(
+        BaseLib::extractBaseNameWithoutExtension(file_name));
+    return MeshLib::VtkMeshConverter::convertUnstructuredGrid(vtkGrid,
+                                                              mesh_name);
 }
 
 MeshLib::Mesh* VtuInterface::readVTKFile(std::string const& file_name)
@@ -161,6 +164,5 @@ int writeVtu(MeshLib::Mesh const& mesh, std::string const& file_name,
     return 0;
 }
 
-
-} // end namespace IO
-} // end namespace MeshLib
+}  // end namespace IO
+}  // end namespace MeshLib