Moonlight, deservedly, ultimately walked away from Sunday's Oscars ceremony with the big award of the night: Best Picture. But the victory itself was unfortunately wrapped up in one of the most bizarre and perplexing moments in Oscars history, as La La Land was initially announced as the winner before a shocked Dolby Theatre audience was alerted to what presenter Warren Beatty quickly explained away as an envelope error.

In a statement from Academy Awards accountants PricewaterhouseCoopers (PwC) released early Monday, Beatty's envelope error explanation was confirmed. Additionally, PwC said an investigation had been opened regarding the royal fuck-up.

"We sincerely apologize to Moonlight, La La Land, Warren Beatty, Faye Dunaway, and Oscar viewers for the error that was made during the award announcement for Best Picture," the statement said. "The presenters had mistakenly been given the wrong category envelope and when discovered, was immediately corrected. We are currently investigating how this could have happened, and deeply regret that this occurred. We appreciate the grace with which the nominees, the Academy, ABC, and Jimmy Kimmel handled the situation."

In a Fortune feature published the day before the Oscars broadcast, PwC co-head Martha Ruiz explained the strenuous process behind counting Academy votes and preparing the final winners list. Ruiz and fellow PwC co-head Brian Cullinan personally stuff the envelopes and stand backstage during the ceremony to hand them out. "Until the presenters open up the envelope on stage and announce [the winner], not even they know who wins," Ruiz said. "It's only the two of us."

Justin Horowitz, La La Land producer, spoke with Good Morning America Monday morning and used the very reasonable adjective "surreal" to describe the fuck-up. "I wanted to make sure the right thing was done," Horowitz said. "At that point it was not about me, it was about making sure Moonlight got the recognition it really deserves." The lesson here, it seems, is simple: Double check your envelopes.