Dallas Cowboys running back Ezekiel Elliott had a rookie campaign for the ages, rushing for a league-best 1,631 yards and 15 touchdowns, earning him Rookie of the Year and first-team All-Pro honors.

The star running back can add another job title to his resume: signature expert, and the one he’s an expert on is his own.

Elliott called out several people on Twitter that were trying to sell memorabilia they claimed was signed by the former Ohio State standout.

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Ezekiel Elliott Autographed Signed Ohio State Dallas Cowboys Mini Helmet COA & Hologram by.. https://t.co/nitQVXSPka — kittenbargain #fb (@kittenbargain) February 9, 2017

Then this…

Ezekiel Elliott Autographed Signed Ohio State 8 x 10 Photo – Near Mint Condition – COA by Nostalgic.. https://t.co/XO9ZMZcSPN — resultminutes1 (@resultminutes1) February 10, 2017

Elliott then had to break the news to a fan, who asked him to authenticate a recent gift he got for Christmas.

@EzekielElliott hey, saw you call out that account for a fake autographed helmet, received this one for xmas, please tell me real! pic.twitter.com/VxpaOnVxJY — Blake Nelsen (@Bliz2DaIz) February 10, 2017

Perhaps Elliott will send this guy a real piece of autographed memorabilia. But to be fair, that signature is way too clean to be that of an athlete. Red flag No. 1.