Hosted in Poland, Open'er is part of a wave of festivals helping to link Eastern Europe to the summer season.
Seemingly to grow each year, the event will return this summer with a bumper line up. In a new announcement, organisers have confirmed that Lykke Li is set to appear at Open'er.
Marking a rare return to Polish soil, Lykke Li is set to unveil material from her upcoming album 'I Never Learn'.
The new additions join a bill already peppered with star names, as Open'er prepares to welcome Pearl Jam, the Black Keys, Warpaint, Interpol and more.
Tickets are on sale now.
Open'er runs between July 2nd - 5th.