Jack Johnson will fill in for Mumford and Sons during tomorrow night’s headlining slot at Bonnaroo. The English folk-rock superstars were forced to cancel their appearance at the festival, and the remainder of their summer tour, following the discovery of a blood clot in bassist Ted Dwayne’s brain. Dwayne underwent emergency surgery and appears to recovering smoothly, but the band decided to call off the shows anyway due to the medical advice they received.

As previously reported, Johnson already sat in with ALO last night during their late night performance in the That Tent. Jackson also headlined the festival back in 2008 and was one of the breakout stars of the first Bonnaroo in 2002.