Run DMC and Aerosmith’s version of “Walk This Way” might be one of the most important singles ever released – but Run-DMC was afraid it would ruin their careers.

Darryl ‘DMC’ McDaniels told People the group initially had no interest when producer Rick Rubin suggested the collaboration.

He said “We thought it was going to ruin our careers… We had no idea that everybody from Red Alert to Grandmaster Flash would say, ‘Yo, that’s the coolest thing.'”

Of course, “Walk This Way” became a massive hit and was one of the first hip-hop videos in heavy rotation on MTV.