adding preprocessor defines in module makefiles

Hi, I'm trying to build a kernel module for fun, and I can't figure out a clean way to add preprocessor defines that correspond to Kconfig values. I'm trying to set CONFIG_SND_DEBUG specifically. My module has only one file, and I've tried adding #define CONFIG_SND_DEBUG as the first line in the .c file, but now I'm getting the following warning: WARNING: "__snd_printk" [/home/chris/snd/snd-foo.ko] undefined! I haven't compiled the kernel running on my system with the CONFIG_SND_DEBUG option but I haven't been able to see a reason why that should change anything for my module. thanks, Chris