diff --git a/src/gpu/VirtualFluids_GPU/LBM/Simulation.cpp b/src/gpu/VirtualFluids_GPU/LBM/Simulation.cpp
index 38b6b6fa571ecaa80e9b31b87d71f1c14da78976..b9d469d0e39d15413ff397faaadd400f3aa6f480 100644
--- a/src/gpu/VirtualFluids_GPU/LBM/Simulation.cpp
+++ b/src/gpu/VirtualFluids_GPU/LBM/Simulation.cpp
@@ -17,7 +17,7 @@
 //////////////////////////////////////////////////////////////////////////
 #include "Output/MeasurePointWriter.hpp"
 #include "Output/AnalysisData.hpp"
-#include "Output/InterfaceDebugWriter.hpp"
+#include "Output/InterfaceDebugWriter.h"
 #include "Output/EdgeNodeDebugWriter.hpp"
 #include "Output/NeighborDebugWriter.h"
 #include "Output/VeloASCIIWriter.hpp"
diff --git a/src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.hpp b/src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.cpp
similarity index 99%
rename from src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.hpp
rename to src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.cpp
index da5307c3d8080d7d10ad91dc970639fdd83dd2dc..5e96db99e17a0908ed9549af3c89ee48cf9db8d3 100644
--- a/src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.hpp
+++ b/src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.cpp
@@ -1,15 +1,14 @@
-#ifndef INTERFACEDEBUG_HPP
-#define INTERFACEDEBUG_HPP
-
 #include <fstream>
 #include <sstream>
+#include <cmath>
+
+#include "InterfaceDebugWriter.h"
 #include "StringUtilities/StringUtil.h"
-#include "lbm/constants/D3Q27.h"
+#include <lbm/constants/D3Q27.h>
 #include "LBM/LB.h"
 #include "Parameter/Parameter.h"
-#include "basics/utilities/UbSystem.h"
+#include <basics/utilities/UbSystem.h>
 #include <basics/writer/WbWriterVtkXmlBinary.h>
-#include <cmath>
 
 namespace InterfaceDebugWriter
 {
@@ -601,7 +600,7 @@ void checkForSendNodeZ(int pos, int &sendDir, int &sendDirectionInCommAfterFtoC,
                            para->getParH(level)->sendProcessNeighborsAfterFtoCZ, 8.0);
 }
 
-void writeInterfaceFCC_Send(Parameter *para, int processID = 0)
+void writeInterfaceFCC_Send(Parameter *para, int processID)
 {
     std::vector<UbTupleFloat3> nodesVec;
     int nodeNumberVec = 0;
@@ -655,7 +654,7 @@ void writeInterfaceFCC_Send(Parameter *para, int processID = 0)
     }
 }
 
-void writeInterfaceCFC_Recv(Parameter *para, int processID = 0)
+void writeInterfaceCFC_Recv(Parameter *para, int processID)
 {
     std::vector<UbTupleFloat3> nodesVec;
     int nodeNumberVec = 0;
@@ -716,7 +715,7 @@ void addToNodesVector(const int level, const int pos, std::vector<UbTupleFloat3>
     nodesVec.push_back(makeUbTuple((float)(x1), (float)(x2), (float)(x3)));
 }
 
-void writeSendNodesStream(Parameter *para, int processID = 0)
+void writeSendNodesStream(Parameter *para, int processID)
 {
     std::vector<UbTupleFloat3> nodesVec;
 
@@ -813,7 +812,7 @@ void writeSendNodesStream(Parameter *para, int processID = 0)
     }
 }
 
-void writeRecvNodesStream(Parameter *para, int processID = 0)
+void writeRecvNodesStream(Parameter *para, int processID)
 {
     std::vector<UbTupleFloat3> nodesVec;
 
@@ -900,4 +899,3 @@ void writeRecvNodesStream(Parameter *para, int processID = 0)
 }
 
 } // namespace InterfaceDebugWriter
-#endif
diff --git a/src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.h b/src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.h
new file mode 100644
index 0000000000000000000000000000000000000000..6a13f9bb48f5db7aced0009f58c87d773422f9c1
--- /dev/null
+++ b/src/gpu/VirtualFluids_GPU/Output/InterfaceDebugWriter.h
@@ -0,0 +1,40 @@
+#ifndef INTERFACEDEBUG_HPP
+#define INTERFACEDEBUG_HPP
+
+class Parameter;
+namespace InterfaceDebugWriter
+{
+
+void writeInterfaceLinesDebugCF(Parameter *para);
+void writeInterfaceLinesDebugFC(Parameter *para);
+
+void writeInterfaceLinesDebugCFCneighbor(Parameter *para);
+void writeInterfaceLinesDebugCFFneighbor(Parameter *para);
+void writeInterfaceLinesDebugFCCneighbor(Parameter *para);
+void writeInterfaceLinesDebugFCFneighbor(Parameter *para);
+
+void writeInterfaceLinesDebugOff(Parameter *para);
+void writeInterfacePointsDebugCFC(Parameter *para);
+
+void writeBcPointsDebug(Parameter *para);
+void writePressPointsDebug(Parameter *para);
+void writePressNeighborPointsDebug(Parameter *para);
+
+void writeNeighborXPointsDebug(Parameter *para);
+void writeNeighborXLinesDebug(Parameter *para);
+void writeNeighborYPointsDebug(Parameter *para);
+void writeNeighborYLinesDebug(Parameter *para);
+void writeNeighborZPointsDebug(Parameter *para);
+void writeNeighborZLinesDebug(Parameter *para);
+
+void writeInterfaceCellsDebugCFC(Parameter *para);
+void writeInterfaceCellsDebugCFF(Parameter *para);
+
+void writeInterfaceFCC_Send(Parameter *para, int processID = 0);
+void writeInterfaceCFC_Recv(Parameter *para, int processID = 0);
+
+void writeSendNodesStream(Parameter *para, int processID = 0);
+void writeRecvNodesStream(Parameter *para, int processID = 0);
+} // namespace InterfaceDebugWriter
+
+#endif
\ No newline at end of file