diff --git a/apps/tutorials/cuda/01_GameOfLife_kernels.h b/apps/tutorials/cuda/01_GameOfLife_kernels.h
index 8ade238ab555bdcc2f20f7873caa2486d657e257..11f5eeba25800f18b9029092b510a9b36dfe1de0 100644
--- a/apps/tutorials/cuda/01_GameOfLife_kernels.h
+++ b/apps/tutorials/cuda/01_GameOfLife_kernels.h
@@ -1,3 +1,5 @@
+#pragma once
+
 #include <iostream>
 
 #include "cuda/FieldAccessor.h"
diff --git a/src/blockforest/loadbalancing/DynamicParMetis.h b/src/blockforest/loadbalancing/DynamicParMetis.h
index a39bc7c76238913d72dd3fb57d2e1dbe8dd2b298..1fa7667ee3aa4932015291edccd2fbd87c336d0b 100644
--- a/src/blockforest/loadbalancing/DynamicParMetis.h
+++ b/src/blockforest/loadbalancing/DynamicParMetis.h
@@ -19,6 +19,8 @@
 //
 //======================================================================================================================
 
+#pragma once
+
 #include "blockforest/PhantomBlockForest.h"
 
 #include "core/DataTypes.h"
diff --git a/src/blockforest/loadbalancing/StaticParMetis.h b/src/blockforest/loadbalancing/StaticParMetis.h
index deb0a41b6a69e4a67a5ba7a501ca769c33f01c7f..85012654d1d170899034d09a50e529e2d78218e9 100644
--- a/src/blockforest/loadbalancing/StaticParMetis.h
+++ b/src/blockforest/loadbalancing/StaticParMetis.h
@@ -19,6 +19,8 @@
 //
 //======================================================================================================================
 
+#pragma once
+
 #include "blockforest/SetupBlockForest.h"
 
 #include "core/DataTypes.h"
@@ -66,4 +68,4 @@ protected:
 
 
 } // namespace blockforest
-} // namespace walberla
\ No newline at end of file
+} // namespace walberla
diff --git a/src/core/load_balancing/MetisWrapper.h b/src/core/load_balancing/MetisWrapper.h
index 3b4ecbfcd01a7272f7ac4ccdc161892b0701755c..042d1f629fe9a9613a92179640ec998934d3bcd9 100644
--- a/src/core/load_balancing/MetisWrapper.h
+++ b/src/core/load_balancing/MetisWrapper.h
@@ -19,6 +19,8 @@
 //
 //======================================================================================================================
 
+#pragma once
+
 #include "core/DataTypes.h"
 #include "core/mpi/MPIWrapper.h"
 
@@ -69,4 +71,4 @@ extern const int METIS_OPTION_GTYPE;
 extern const int METIS_OPTION_UBVEC;
 
 } // namespace core
-} // namespace walberla
\ No newline at end of file
+} // namespace walberla
diff --git a/src/core/load_balancing/ParMetisWrapper.h b/src/core/load_balancing/ParMetisWrapper.h
index 09a7601e8509516a5085b949eae74faff7c9c301..cc3b9a3125121aff462eda26aedfa82de891af82 100644
--- a/src/core/load_balancing/ParMetisWrapper.h
+++ b/src/core/load_balancing/ParMetisWrapper.h
@@ -19,6 +19,8 @@
 //
 //======================================================================================================================
 
+#pragma once
+
 #include "MetisWrapper.h"
 
 #include "core/DataTypes.h"
@@ -52,4 +54,4 @@ int ParMETIS_V3_RefineKway(
    int64_t *part, MPI_Comm *comm );
 
 } // namespace core
-} // namespace walberla
\ No newline at end of file
+} // namespace walberla