Tom Hiddleston made a surprise appearance at Michigan's Wheatland Music Festival this past weekend, where he performed Hank Williams songs ahead of the upcoming release of the country singer's biopic "I Saw the Light."

The 33-year-old British actor, who is best known for his portrayal of Loki in "Thor" and "Avengers" films, entertained concertgoers Saturday, Sept. 6, with a cover of Williams' "Move It On Over." The performance, which is "equal parts dreamy and joyful" according to MTV News, is not a random gig for Hiddleston. Instead, it is sort of a preparation for the actor who will play Williams in the biopic, which begins filming in Louisiana in October.

Watch Hiddleston's version of "Move It on Over" on the video below.

On Sunday, Sept.7, Hiddleston hit the stage again, this time joining Rodney Crowell on a performance of Williams' "I'm So Lonesome I Could Cry," according to Billboard.

But according to Williams' grandson Shelton Hank Williams III, who is also known as Hank3, Hiddleston's performances of his grandfather's hits were not well at all.

"Here is how you do it TOM, You got no Moan Or SOul In your voice," Hank3, wrote on his Facebook page along with a video of himself singing "Move It On Over," according to Fox News.

Hank3 was not really thrilled when he first learned that Hiddleston will play his grandfather in the upcoming biopic.

"To do a Hank Williams movie the way it should be done you need certain aspects in the mix to make right," the singer told Fox News in a statement in June. "It goes way beyond having [an] American to play the role of Hiram Hank Williams, Sr. for it to be somewhat natural, [it] needs to be [an] American from the South who has eat lived and breathed these kind of roles before to make more respectable movie on Hank Sr."

"Matthew McConaughey would be a good person for this role is because of he has played many roles as a Southern man. And he is from the South. And that is something no amount of money or acting classes can put into a role," Hank3 added. "The other reason I thought Matthew would be a good fit for the role is because he has a natural arrogance, aka fire, that is needed for this role. Hank Sr. was very very sure of himself and basically very cocky. And Matthew always brings that fire to the table in every role he [plays]."