Star Trek fans love a good Easter egg. But what about a Star Wars Easter egg in a Star Trek film?

On Monday - you know, Star Trek day - Kirk Thatcher, aka Punk on Bus, aka associate producer on Star Trek IV: The Voyage Home, revealed that he hid a little Star Wars reference in an unassuming scene early in the film. He tweeted out a video of Spock on Vulcan, taking a memory test, along with the caption, “This May the 4th, I am revealing a Star Wars Easter Egg that I wrote into Star Trek IV, that no one has ever caught! The Matron of Vulcan Philosophy, that I created for this was named, T' Plane Hoth....or...mildly unscrambled, Planet Hoth!! #UnitebothFandoms ! So, MTFBWY & LLAP!!”

The Planet Hoth, of course, was featured in the Star Wars film, The Empire Strikes Back, which had been released six years earlier, in 1980.

After Thatcher tweeted out his Easter egg, Dr. Trek himself, Larry Nemecek, also pointed out that T’Plana-Hath, written with an alternate spelling, was the name of the Vulcan ship that made first contact with humans, in the film Star Trek: First Contact.

Of course, this wouldn’t be the last time that a Star Wars reference made it into a Star Trek film...Remember when R2-D2 turned up in Star Trek: Into Darkness? Oh, it happened! It really happened.