Roger Waters joined John Prine onstage Sunday for a surprise appearance during the folk legend’s headlining set at the 2017 Newport Folk Festival. The duo performed an intimate rendition of 1971’s “Hello in There,” a highlight from Prine’s self-titled debut LP.

Waters and Prine tackled the tune by fingerpicking a pair of acoustic guitars, backed by cymbal swells and Lucius’ soulful backing vocals. The former Pink Floyd bassist – who covered “Hello in There” during his 2015 Newport set – handled lead vocals on the second verse and added rugged harmonies throughout.

Prine’s star-studded, fest-closing set featured several other guest performers, including Bon Iver’s Justin Vernon, My Morning Jacket frontman Jim James, Margo Price and Nathaniel Rateliff. The stage flooded with dozens of other festival performers during the closing rendition of “Paradise.”