Foo Fighters headlined Poland’s Open’er Festival last night and welcomed out The Kills’ vocalist Alison Mosshart (who performed prior to the band’s set) to trade vocals with Dave Grohl on the band’s new Concrete and Gold track “La Dee Da.”

Mosshart previously joined the group in Latvia for “The Sky is a Neighborhood” and the aforementioned “La Dee Da.” Grohl mentioned that Mosshart appears on the band’s forthcoming album and The Kills will also play a set at their own Cal Jam later this year.

Foo Fighters’ Concrete and Gold arrives September 15.