As Oregon State quarterback Sean Mannion inches closer to becoming the Pac-12's all-time leading passer, it looks like he might need a couple of more completions to get there than originally thought.

Sean Mannion's chase of Matt Barkley's Pac-12 record for passing yards just got slightly longer. Ralph Freso/Getty Images

A "book-keeping" error on the part of the league, as reported by The Oregonian, shows that current all-time leader Matt Barkley actually has 12,327 career passing yards, not the 12,274 yards he was believed to have at the end of his career with USC.

It's only a difference of 53 yards, which could equate to one deep ball or a few bubble screens and slants. Either way, Mannion, who has 11,339 yards, now needs 988 more passing yards to set the all-time record after throwing for 275 yards in a win last week over San Diego State.

Through three games, Mannion is averaging 301 passing yards per game, which ranks third in the Pac-12 and 17th nationally. He's completing 67.3 percent of his throws, with four touchdowns and a pair of interceptions.

Heading into Saturday's game at USC, Mannion is third on the Pac-12's all-time passing list behind Carson Palmer (11,818).