A downtown Manhattan restaurant has come up with a dimwitted idea to cover up its less-than-stellar city health-inspection grade — placing an illuminated “A” over the “B” displayed in its window.

City workers found evidence of mice, roaches and poor cleaning habits at the East Village’s Downtown Bakery when they visited there Oct. 3, and slashed its rating from an “A” to a “B.”

But the glass frame displaying the grade in the First Avenue joint has a trick — it lights up with a bright blue “A”, eclipsing the actual grade.

And the misleading display did not sit well with passers-by.

“It makes me think that someone’s doing something fraudulent,” said Belinda Johnson.

An employee claimed it’s all a misunderstanding, saying the eatery used to have an “A,” but employees forgot to change the frame when the restaurant rating was downgraded nearly a month ago.

“We don’t want to mislead anyone,” said the worker, who gave the name Coco.

The eatery got an “A” rating during a previous inspection in February — although evidence of mice and roaches was noticeable then, too, city records show.

Staff had ample opportunity to realize the display was misleading — it fell on the floor once before someone put it back up — and after that, it began to malfunction and blink, which someone pointed out to workers, Coco said.

“Maybe a week and a half ago, someone brought it to our attention,” he said.

The city will look into the letter-grade modifier, according to Health Department rep Julien Martinez.

“Obstructing a restaurant letter grade is a serious violation that puts consumers at risk,” he said.