Manchester United were forced to correct an error on their official website when it was pointed out by an Arsenal supporter.
Online, the Red Devils wrote that the club have won a record 11 FA Cups, but Gunners fan Jeremy Livingston was quick to get in touch to correct them.
Last season, Arsenal added a 12th victory to their FA Cup triumphs at Wembley, surpassing United's total, which the Premier League giants have now recognised.
Mr Livingston tweeted the club and received the reply: "It was indeed just an oversight and, with your help, the statements which were rendered inaccurate by Arsenal's triumph in May have now been corrected."
The Arsenal fan later posted the tweet: "Here's to many more amendments to @ManUtd statements rendered inaccurate by Arsenal's triumphs!"
United last won the FA Cup in 2004.