Thor is getting serious about an issue on Earth.

Chris Hemsworth, who is currently filming the third installment in Marvel’s Thor franchise, posted to Instagram in solidarity with protestors of the Dakota Access Pipeline, a proposed 1,200-mile-long pipeline between oil fields in North Dakota and Illinois.

Members of the Standing Rock Sioux Native American tribe have been protesting to stop the pipeline from crossing next to their reservation, w they say it would destroy sacred sites and contaminate the water supply.

Hemsworth posted a picture of himself in costume standing with Thor: Ragnarok director Taika Waititi and holding a sign that reads, “We stand with Standing Rock.”.

“Standing with those who are fighting to protect their sacred land and water,” he captioned the photo.

Hemsworth also took a moment to acknowledge one of his own failings, in which he wore an offensive costume to a themed party last New Year’s Eve.

“I was at a Lone Ranger themed party w some of us, myself included, wore the traditional dress of First Nations people,” he wrote.

“I was stupidly unaware of the offense this may have caused and the sensitivity around this issue. I sincerely and unreservedly apologize to all First Nations people for this thoughtless action. I now appreciate that t is a great need for a deeper understanding of the complex and extensive issues facing indigenous communities. I hope that in highlighting my own ignorance I can help in some small way.”

Hemsworth isn’t the only celeb to speak out about the DAPL. Shailene Woodley was arrested earlier this month at an anti-DAPL protest.

Chris Hemsworth