One Direction just finished up their fifth night at London's O2 Arena for the On The Road Again Tour, and that's definitely cause for celebration.

But 1D member Niall Horan experienced a hiccup in the festivities that he just had to speak up about. After a paparazzo pushed a fan out of the way to get a photo of him, he took to Twitter to bash them.

"I absolutely hate some of those paps... Nasty nasty people .Whoever the hell you were, don't ever tell one of our fans to get out of the way," Niall wrote on Twitter after he was mobbed around Cirque le Soir. "So you can get a sh-t picture of me walking into a nite club that you'll get 10 quid ... You do nothin for me , so you get out of the way."

Tell 'em, Niall!

A fan who was there agreed that the paparazzi were being way mean:

But that didn't stop Niall from taking pictures with fans last night, even though he was clearly ticked.

The guys of One Direction will be heading back to London on Nov. 14, a day after they release their fifth album, Made in the A.M. They're holding a special, secret concert with Apple Music for fans to celebrate the new LP.