Bolt it down. I went this route once with a pistol safe under the nightstand un-attached. When my house was broken into back in May the theives took the whole safe along with the 3 handguns, 2 holsters, ammo and spare mags inside.
I'm kicking myself for not taking the 15 minutes to bolt it down.
Its a nice piece of furniture, and I'm not convinced that a couple screws would not keep someone from popping it off. Its the only gun out of the safe, not on my person. It only holds one pistol and a spare mag.