Officers in a St. Louis suburb don't have to worry about making sure they have cash to pay for their lunch, thanks to the generosity of a local resident.

The "mystery man" picks up the tab for local police officers stopping in for sandwiches at Protzel’s Deli in Clayton, just outside St. Louis.

“My ruling is, if you take care of people like that, you’ll get it back 10-fold,” the man, who wished to remain unidentified, told FOX 2.

He's been picking up the tab for officers' lunches at the deli for over a year, contributing a particular amount of cash to the establishment to pay for the sandwiches.

Local law enforcement said they are just grateful for the man's generosity.

“We see a lot of negativity in our job. Bad accidents, domestic-related issues, assaults, burglaries, robberies. So it’s always nice on the other side of that job, when we’re not dealing with those types of calls – and we go somewhere and we see people thanking us,” St. Louis County Police Spokesman Sgt. Shawn McGuire told FOX 2.

Some officers have figured out who the generous donor is, and gone out of their way to thank them.

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“I’ll have to say, once in a while, they’ll just stop and they’ll just give me a thumbs up, or they’ll come over and shake my hand,” the man said.

Law enforcement said the man's simple gesture of kindness goes a long way.

“That’s really cool to think about. And it really touches our hearts,” McGuire said.