5 Seconds of Summer are having "late night jamz" with the Madden Brothers.
The Australian band - which is made up of Luke Hemmings, Ashton Irwin, Michael Clifford and Calum Hood - appear to be collaborating with the duo on their new album.
In a photograph posted by Joel Madden, Luke, Ashton, his brother Benji and others can be seen crowding around a table as they pose for a photograph.
In another picture uploaded to Instagram on Sunday (08.02.15), Joel and Benji posed with Ashton, Michael and legendary music producer John Feldmann.
The brotherly duo - who found fame as members of rock band Good Charlotte - have worked alongside the 'She Looks So Perfect' hitmakers before, having writing credits on the band's track 'Amnesia', which was certified Platinum in the United States.
Meanwhile, Benji - who recently married Cameron Diaz - previously admitted that he felt as though the four-piece band were a "younger version" of him and his fellow Good Charlotte members.
He said: "But 5 Seconds of Summer remind me of Good Charlotte in the best possible way. They're a younger us. I'm glad they're doing this sound and I'm very happy to pass the torch.
"The thing is, me and Joel have always written pop songs - we just dress them up differently. We actually wrote 5SOS's song 'Amnesia', and it's [good] to see that sound coming back and being a part of it.
"Back in the day we often felt the brunt of being a rock band singing pop melodies. I'm glad it wasn't for nothing!"
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