Wondering if it's possible to be able to lock the doors to the STi, when the car is running?

It was cold this morning, so I wanted to have the car running for a bit, to defrost the windows (I didn't have the heart to scrape the brand new windshield), but I couldn't lock the doors. My neighbourhood isn't bad, by any means, but I also didn't want to leave the car unlocked, with the keys in the ignition.

Any way to do this?