If you're happy and you know it, keep it to yourself.
Four states have outlawed smiling on driver's license pictures in an attempt to make the photos more accurate, USA Today reported.
Drivers in Arkansas, Indiana, Nevada and Virginia will have to ham it up for the camera without flashing their pearly whites -- license-holders in those areas will be forced to adapt "neutral facial expressions" as their pictures are snapped..
Eliminating smiling helps alert the DMV to potential identity theft through facial-recognition software -- neutral faces are easier to compare with previous pictures of license holders.
The emotionless expressions "make the comparison process more accurate," said Karen Chappell, deputy commissioner of the Virginia DMV.
Virginia's policy is strictly anti-smile, but Arkansas, Indiana and Nevada drivers are allowed to crack a slight grin.
"You just can't grin really large," Arkansas driver services chief Tonie Shields told USA Today.
Photo-matching software has already helped recognize thousands of instances of identity theft, several state DMV officials said.