diff --git a/sample/c++/Nbody/Makefile b/sample/c++/Nbody/Makefile
index e48c738..c8ee750 100644
--- a/sample/c++/Nbody/Makefile
+++ b/sample/c++/Nbody/Makefile
@@ -13,16 +13,19 @@ SRC=nbody.cpp
 ifeq ($(use_avx2),yes)
 CONVERSION_TYPE=AVX2
 CCFLAGS += -mavx2 -mfma -ffast-math
+HED = kernel.hpp
 endif
 
 ifeq ($(use_avx512),yes)
 CONVERSION_TYPE=AVX-512
 CCFLAGS += -mavx512f -mavx512dq -ffast-math
+HED = kernel.hpp
 endif
 
 ifeq ($(use_arm_sve),yes)
 CONVERSION_TYPE=A64FX
 CCFLAGS += -Kfast
+HED = kernel.hpp
 endif
 
 ifeq ($(use_cuda),yes)
@@ -34,6 +37,10 @@ CCFLAGS+= -DUSE_CUDA_KERNEL
 NVCCFLAGS= $(CCFLAGS)
 endif
 
+ifeq ($(CONVERSION_TYPE),reference)
+HED = kernel.hpp
+endif
+
 all:	nbody.out
 kernel.cu:	kernel.pikg
 	$(PIKG) $(PIKG_OPTION) --output $@ -i $<
@@ -41,8 +48,8 @@ kernel.o:	kernel.cu
 	$(NVCC) $(NVCCFLAGS) $< -c -o $@
 kernel.hpp:	kernel.pikg
 	$(PIKG) $(PIKG_OPTION) --output $@ -i $<
-nbody.out:	$(SRC)
-	$(CC) $(CCFLAGS) $^ -o $@
+nbody.out:	$(SRC) $(HED)
+	$(CC) $(CCFLAGS) $(SRC) -o $@
 test:	nbody.out
 	./nbody.out
 clean: