For a marriage to work, one has to make adjustments and try to understand a few of their spouse’s quirk. For the royal couple Prince Harry and Meghan Markle, the Duchess of Sussex has to live with her royal husband’s penchant for turning off the lights at night.

Apparently, Prince Harry has this obsession with turning off the light when they’re not really in use. And he blames his father, Prince Charles, for instilling this energy-saving habit. “He’s a stickler for turning lights off,” the Duke of Sussex said. “And that’s now something that I’m obsessed with as well.”

The habit even rubbed off on Prince William as well. “I know, I’ve got serious OCD on light switches now, which is terrible,” the Duke of Cambridge admitted.

Of course, that wouldn’t have been an issue if Meghan herself prefers a darker house, except that she doesn’t. “Meghan literally said she hates the dark — I don’t know if she’s afraid of the dark but she hates the dark — but literally she’ll walk out of a room and he’ll hit the light,” according to “The Real Daytime” host Adrienne Bailon.

Even Prince Harry admitted that his lighting preference has been a cause of debate between him and Meghan. “My wife certainly goes, ‘Well, why turn the lights off? It’s dark,’” Harry revealed. “I go, ‘We only need one light, we don’t need, like, six,’ and all of a sudden, it becomes a habit.”

It looks like Prince Charles has successfully passed on to his sons his passion for conserving the environment. “All of a sudden it becomes a habit and those small habit changes he’s making, every single person can do,” explained Prince Harry. “And I think it’s one of the key lessons that [Prince Charles] taught us.”

For the record, it’s not only Prince Charles and his children who have the habit of turning off the lights. Despite having a personal net worth of around $500 million, Queen Elizabeth II also tries to save on energy costs by making sure unused light are all turned off.

“The attention is drawn of all members of staff to the need to switch off unwanted lights. By Order of The Master of The Household,” reads the numerous signs posted all over the palace. Palace employees even say that Her Majesty would sometimes roam the halls to personally switch off the lights.

Meghan Markle and Prince Harry Prince Harry, Duke of Sussex, and Meghan, Duchess of Sussex, attend the Commonwealth Day service at Westminster Abbey on March 11, 2019, in London, England. Samir Hussein/Samir Hussein/WireImage