building kernel modules for linux differnet version

Hi, I have a scenario where I need to build a driver for different kernel versions. I have kernel-headers of different version in /lib/modules/ 2.6.32-xxxx 2.6.39-xxxx and currently I am booted into 2.6.32-xxxx(which I find out by uname -r) Now in my driver makefile, I generate .ko of driver make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules but I notice that the driver .ko gets generated for 2.6.39-xxxx though I am booted into 2.6.32-xxxx. Can anyone help me figure out why this is happening? Regards, Saket Sinha