(CNN) -- You'll have to be doggedly clever to unlock Mike Linden's new iPhone 5S.
Linden, 23, was fooling around with the fingerprint sensor on the iPhone he purchased Friday morning. He found it dull locking and unlocking it with his own finger, so he decided to find out what would happen if he programmed the front right paw of his pet Chihuahua, Hurley, into the gadget.
Much to his surprise, the pawprint did the job.
"I thought this is never going to work, and it did!" Linden told CNN iReport. "The funniest thing is, it only works for the paw I programmed. It doesn't work for the other three."
Dogs aren't the only four-legged friends who can handle the sensor. TechCrunch found it has worked for cats, too.
Linden, a musician in Burnsville, Minnesota, is an Apple fan: He was in line at Minnesota's Mall of America at 4:45 a.m. to be among the first to get the new iPhone.
The phone has a fingerprint sensor in its Home button for added security. Users must "register" their print with the device, after which they can unlock the phone by placing a finger or thumb on the button.
But though he's been tickled by the finger (paw?) print sensor, Linden's not too pleased with the particular phone he bought. The sound from the phone receiver is muffled and he suspects he'll have to return it.
When he does, Hurley might not be as cooperative.
"The more I do it the angrier he gets," Linden said. "I've tried all the paws now and he put up quite a fight to get the back ones on there. I have to give him a lot of treats."
Hmm. Treats. Perhaps a new Apple marketing strategy?