diff --git a/example/Vector/7_SPH_dlb_gpu_opt/Makefile b/example/Vector/7_SPH_dlb_gpu_opt/Makefile
index cca7077fdc1c3c4229ec9ad16db9200ea740a8f1..ce1336a5d73aa5906577a50b5c12e4a8e8f9a76d 100644
--- a/example/Vector/7_SPH_dlb_gpu_opt/Makefile
+++ b/example/Vector/7_SPH_dlb_gpu_opt/Makefile
@@ -12,10 +12,10 @@ sph_dlb_test: OPT += -DTEST_RUN
 sph_dlb_test: sph_dlb
 
 %.o: %.cu
-	nvcc -O0 -g -c -isystem=/home/i-bird/MPI/include --std=c++11 -o $@ $< $(INCLUDE_PATH_NVCC)
+	nvcc -O3 -g -c -isystem=/home/i-bird/MPI/include --std=c++11 -o $@ $< $(INCLUDE_PATH_NVCC)
 
 %.o: %.cpp
-	$(CC) -O0 $(OPT) -g -c --std=c++11 -o $@ $< $(INCLUDE_PATH)
+	$(CC) -O3 $(OPT) -g -c --std=c++11 -o $@ $< $(INCLUDE_PATH)
 
 sph_dlb: $(OBJ)
 	$(CC) -o $@ $^ $(CFLAGS) $(LIBS_PATH) $(LIBS)
diff --git a/src/Vector/cuda/vector_dist_cuda_funcs.cuh b/src/Vector/cuda/vector_dist_cuda_funcs.cuh
index 3e119645e6e1aa4564cf0f8212e94c74b5e599d5..5a0874a8dee9e60bc61a48ee4a435dce80476628 100644
--- a/src/Vector/cuda/vector_dist_cuda_funcs.cuh
+++ b/src/Vector/cuda/vector_dist_cuda_funcs.cuh
@@ -373,7 +373,13 @@ void remove_marked(vector_type & vd)
 
 	// we have no particles to remove
 	if (*(int *)mem.getPointer() != 1)
-	{return;}
+	{
+		if (*(int *)mem.getPointer() >= 2)
+		{
+			std::cout << __FILE__ << ":" << __LINE__ << " error: removing marked particle. Carefull particle must be marked with 1 or 0, no other numbers" << std::endl;
+		}
+		return;
+	}
 
 	// Get the mark point
 	mark.template deviceToHost<0>();