diff --git a/src/gpu/VirtualFluids_GPU/BoundaryConditions/BoundaryConditionFactory.h b/src/gpu/VirtualFluids_GPU/BoundaryConditions/BoundaryConditionFactory.h
index aca98c968c3cd226520bf6a7e2a9115cc1f21b8c..099423fcf08bd028fb667e4f584adaef2b4c071a 100644
--- a/src/gpu/VirtualFluids_GPU/BoundaryConditions/BoundaryConditionFactory.h
+++ b/src/gpu/VirtualFluids_GPU/BoundaryConditions/BoundaryConditionFactory.h
@@ -7,7 +7,7 @@
 
 #include "LBM/LB.h"
 
-class LBMSimulationParameter;
+struct LBMSimulationParameter;
 
 using boundaryCondition = std::function<void(LBMSimulationParameter *, QforBoundaryConditions *)>;
 
diff --git a/src/gpu/VirtualFluids_GPU/KernelManager/LBKernelManager.h b/src/gpu/VirtualFluids_GPU/KernelManager/LBKernelManager.h
index 6bcdf6b25bf10d56c8d40f37bf68532d2fd91df6..b98469907e52241bed21758cbddaa126d97a2ebc 100644
--- a/src/gpu/VirtualFluids_GPU/KernelManager/LBKernelManager.h
+++ b/src/gpu/VirtualFluids_GPU/KernelManager/LBKernelManager.h
@@ -43,7 +43,7 @@
 class CudaMemoryManager;
 class BoundaryConditionFactory;
 class Parameter;
-class LBMSimulationParameter;
+struct LBMSimulationParameter;
 
 using boundaryCondition = std::function<void(LBMSimulationParameter *, QforBoundaryConditions *)>;