Three decades ago, Michael Jackson recorded a series of duets with Queen frontman Freddie Mercury. Though a handful of tracks were captured on tape, the pair had a falling out shortly after the sessions and the songs never saw the light of day.

Now though, Queen guitarist Brian May has been working on the recordings, which will be released some time this fall. The Jackson estate granted him permission to work on the recordings, and May has been tinkering on and off for two years with fellow Queen member Roger Taylor and producer William Orbit (who famously twiddled the knobs for Madonna’s Ray of Light). The trio has been adding new guitar parts and vocal harmonies to the demos, which were first captured in Jackson’s home studio in Encino, California.

“There are a few items in progress,” May wrote on his blog. “We will have something for folks to hear in a couple of months’ time, hopefully.” He described the work as “exciting, challenging, emotionally taxing. But cool.”

May has time now that the biopic about Mercury has stalled — Sacha Baron Cohen, who was supposed to play Mercury, recently bowed out of the flick, citing irreconcilable difference. The search is now on for an actor to replace Cohen and portray the legendary late frontman.

There’s no indication of what the Jackson-Mercury sessions might have sounded like, though they could offer up some important insight into Jackson’s mindset in the midst of his post-Thriller victory lap. It would be another four years before Jackson would release Bad, so the music he created between Thriller and its follow-up will make for a fascinating historical footnote.