The Irish popstar had apparently told the female fan he wasn't up to taking a selfie with her as he was feeling sick, which meant he was stunned to see an image floating around Twitter this week showing him sleeping on the flight.
An explanation next to the picture said: "I sat directly next to Niall from One Direction for nine hours on my flight home from London last night. He was sick and asked for no selfies but here is a pic I snapped while he was sleeping lol. He was so friendly."
Niall, however, wasn't amused, and retweeted the whole message with the caption: "I think this sh*t is unreal. I mean if you can't sleep on a plane without people taking photos of you, what can u do."
I think this shit is unreal. I mean if you can't sleep on a plane without people taking photos of you,what can u do pic.twitter.com/3UvgLpHOcE— Niall Horan (@NiallOfficial) August 2, 2016
Niall's post has been retweeted 85,000 times and favourited 150,000 times.
As you'd expect, numerous One Direction fans were on Niall's side, saying he's entitled to his privacy, particularly when he's already said he can't take photos as he was feeling poorly.
@NiallOfficial Lack of privacy in this famous world sucks I'm so sorry— lay (@dinahjstyles) August 2, 2016
its the cons of being in the world's biggest boyband :( im sorry Niall, theres always gonna be people like this :( @NiallOfficial— larrywhoran (@bkhyunvocals) August 2, 2016
@NiallOfficial this makes me mad. You deserve privacy— Britt (@vaporharry) August 2, 2016
@NiallOfficial sorry that people suck at respecting your privacy :(— l a u r a (@lauraft182) August 2, 2016
@NiallOfficial this is real disrespectful, honestly. You have the right to have your privacy and people don't give it to you.— deb (@stringslad) August 2, 2016