If you're gonna come at Julia Roberts on Instagram, better make your insult bulletproof.

The actress had a great comeback to a fellow Insta user who decided to take her up on her choice of nail polish - yes, nail polish - during a recent red carpet shot from the Toronto International Film Festival.

It seems that despite having 1.6 million followers on the social media platform, Roberts still reads comments on other accounts about herself - and she took the person in question to task with a pretty good comeback, as documented by the CommentsByCelebs account.

This is precisely what the 'nail polish' emoji was made for, after all.

See it below: