Woody Harrelson‘s commitment to an eco-friendly lifestyle is no mystery: the Cheers star is a die-hard vegan and has taken on many environmental projects in the past, including a poker tournament to promote hemp-based biodiesel. Now, Harrelson is championing the rights of a group of chimpanzees.

The subjects of the debate are 186 chimps used by the National Institutes of Health for testing of various products and procedures. The chimps were due to be moved from an animal sanctuary to a medical lab until Harrelson, along with PETA, intervened.

In a letter to the NIH, Harrelson wrote: “These aging chimpanzees… have endured decades of violence and torment, having been used in everything from space experiments to high-velocity seat belt tests. Only in the last few years have they enjoyed bedding, fruit, toys, the touch and companionship of other chimpanzees, and freedom from the knife. Will you please return the 14 chimpanzees… to these simple pleasures and allow them to continue the rehabilitation that they have more than earned?”

Harrelson’s letter must have made an impact, as the NIH canceled the move and will perform an investigation to “reassess the scientific need for the continued use of chimpanzees.” Maybe the NIH heard the stories about his encounters with paparazzi “zombies” and figured it would be best to listen to what he had to say.