Fans have spotted something hysterically wrong with this photo of Kelly Osbourne.

Kelly Osbourne spent her Easter Sunday relaxing in the pool with her sister-in-law Lisa in matching swimmers.

She enjoyed the day so much that she decided to share it with her 2.2 million followers on Instagram.

Nothing wrong with that, right?

Except for the fact there seems to be something very, very, hilariously wrong with Kelly's left arm.

Fans were quick to point out that it appeared the 32-year-old singer and television presenter was suffering from a severe case of "baby arm".

"WHY IS YOUR HAND SO SMALL?" one fan wrote on the photo, while another commented, "Never noticed your tiny left arm before. LOL!"

Luckily, Kelly was able to see the funny side of the situation, posting an explanation for why the arm in the photo was so tiny.

It turns out, the teeny arm belongs to her one-year-old niece, Andy.

Check out my sexy baby arm!The most hysterical yet #epic #PhotoFail! This is instant karma For trying to hide my fat ass behind Lisa while holding my niece! ????

A post shared by Kelly! (@kellyosbourne) on Apr 16, 2017 at 9:35pm PDT

"Check out my sexy baby arm!" she wrote.

"This is instant karma for trying to hide my fat ass behind Lisa while holding my niece!"

LISTEN: Mia Freedman makes on a case for realistic images on Instagram.

Have you ever had a photo fail like Kelly Osbourne? Tell us in the comments below!