Growing up is hard to do... and this little girl has just discovered that it's even harder to watch somebody else doing it.
Sadie, five, has just learnt that her three-month-old brother Carson, won't be a baby forever and she's devastated.
"I don't want him to grow up!" she wails. " He's so cute."
Even worse, the realisation has brought with it a troubling understanding of her own mortality:
"And I don't want to die when I'm one hundre-ed-ed-ed-ed," she adds.
Carson on the other hand seems quite pleased with the idea of growing up as he nods and smiles while his sister sobs.
"Oh you are so cute. I love your cute little smiles," says Sadie. "Oh my gosh I want him to stay this little."
A sentiment shared by many a mum and dad looking down at their smiling baby, although we're sure Sadie will be appeased once she realises that as Carson gets older he'll be able to join in more games.
"She's cried about not wanting to get older herself in the past, but this was the first time she was upset about her brother," Sadie and Carson's father Ryan said in an email statement to TIME magazine.
"The funny thing is that this was totally out of the blue - we have no idea what prompted it."
Since being uploaded to YouTube by the children's uncle, Alex Miller, the clip has racked up more than one and a half million views in just three days.
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See: This boy's hilarious reaction to holding his baby sister for the first time