Mark Hamill is angry that there are those out there duping fans by selling items with fake “Mark Hamill” autographs.

In an attempt to help his fans, the Star Wars: The Force Awakens star took to Twitter Sunday night to help fans figure out whether the autograph in their possession is real or fake.

In a word- NO. I'm so sorry there's so many fans spending their hard-earned money for fraudulent signatures. #FAKE https://t.co/717Bv02ASA

— Mark Hamill (@HamillHimself) December 27, 2015

Hamill, 64, suggested that fans post a photo of their merchandise and he said he would tell them if the signature was legit or not legit.

“I’m so sorry there’s so many fans spending their hard-earned money for fraudulent signatures,” Hamill said in a tweet.

That one is REAL- go for it! (but only at a reasonable price!) #Authentic https://t.co/SxZw59MDti

— Mark Hamill (@HamillHimself) December 28, 2015

Memorize this REAL signature and you can start spotting the phonies yourself! #BeatTheDealers https://t.co/yB0aVXY74E

— Mark Hamill (@HamillHimself) December 28, 2015

Hope everyone can learn my real signature to help prevent fraudulent dealers! #BeatTheDealers #FansRule https://t.co/ViR1kmZJNP

— Mark Hamill (@HamillHimself) December 28, 2015

Throughout the years, there have been some pieces that Mark Hamill did sign so he wanted to help his fans learn how to spot a fake autograph.

.@StarWars actor @HamillHimself skips promotional appearance to visit sick kids https://t.co/ZYIvXBFZuX pic.twitter.com/LCRikdy9G5

— CNN (@CNN) December 24, 2015

Hamill reprised his iconic role as Luke Skywalker for the latest, record-breaking installment of the epic space adventure.

As of Sunday, J.J. Abrams’ installment soared past $1 billion globally faster than any film in history. The movie which reunited Mark Hamill, Harrison Ford and Carrie Fisher in their iconic roles had the biggest Christmas weekend ever at the North American box office with $153.5 million for an early domestic haul of $544.6 million, according to The Hollywood Reporter.