diff --git a/testbench/test_c/Makefile b/testbench/test_c/Makefile
index 4641d8c..949d1a5 100644
--- a/testbench/test_c/Makefile
+++ b/testbench/test_c/Makefile
@@ -39,7 +39,7 @@ LDFLAGS = -melf32lriscv_ilp32
 
 %.o: %.c
 %.s: %.c
-	$(CC) $(CFLAGS) -S $^ -o $@
+	$(CC) $(CPPFLAGS) $(CFLAGS) -S $^ -o $@
 
 %.elf: %.ld $(OBJ)
 	$(LD) $(LDFLAGS) -T $^ -o $@