How to add '-Dxxx' flags in Makefile?

My makefile of `kpd.ko` is following: ============================ module_name = kpd src_sym = kpd_main a38_kpd util objs = $(addsuffix .o,$(src_sym)) wd = $(shell pwd) EXTRA_CFLAGS+=-DTEST ifneq ($(KERNELRELEASE),) obj-m := $(module_name).o $(module_name)-objs := $(objs) else kver = $(shell uname -r) kd = ../../linux-2.6.32.8 modules: $(MAKE) -C $(kd) M=$(wd) $@ clean: $(MAKE) -C $(kd) M=$(wd) $@ endif ============================= Everything's fine,but I want to add `-DTEST` to EXTRA_CFLAGS. Even if I put $(EXTRA_FLAGS) or other macro into `$(MAKE) -C $(kd) M=$(wd) $@`, Nothing changed in all building process. How should I do to insert `-Dxxx` to original Makefile ?