Stephen Hawking has said it before and he’ll say it again: If extraterrestrials call, do not answer ― at least, not without careful consideration.

The renowned theoretical physicists hosts “Stephen Hawking’s Favorite Places,” a new short film available on the streaming service Curiosity Stream. The film follows Hawking around the universe as he “travels” in a computer-generated imagery spacecraft, giving the audience a peek into simulations of a black hole and Gliese 832c, an earth-like planet outside our solar system that scientists believe may be able to support life.

And Gliese 832c isn’t even the closet possible second-Earth. In August, scientists announced that Proxima b, a planet orbiting Proxima Centauri — the nearest known star to our sun — has a temperature that could allow liquid water and is possibly habitable.

But if we ever get a signal from any of these places, Hawking warns that we shouldn’t be too eager to say hello.

“We should be wary of answering back,” he says in the film, according to USAToday. “Meeting an advanced civilization could be like Native Americans encountering Columbus — that didn’t turn out so well.”

It’s an idea Hawking has expressed numerous times before — typically using human beings as an example of why we shouldn’t trust other intelligent life.

“We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet,” he told The Times of London in 2010. “I imagine they might exist in massive ships, having used up all the resources from their home planet. Such advanced aliens would perhaps become nomads, looking to conquer and colonize whatever planets they can reach.”

Well, we’re convinced. NASA, we really hope you’re listening.