Someone wanted a Mariah Carey birthday cake. They got Marie Curie instead.

Mariah Carey or Marie Curie? A not-so-common mix-up, but one that saw quite the birthday blunder.

In a tweet, author Harriet Alida Lye explained that her cousin, Siobhan, told her colleagues in England she wanted a cake with singer Mariah Carey's face on it -- a perfectly reasonable request for one's birthday.

You'd think one of the world's most recognisable pop stars would be a piece of, uh, cake for most people to organise, but in this case, Lye's cousin received a cake featuring Noble Prize-winning Polish, French-naturalised physicist Marie Curie.

"They misunderstood, and [this] is the cake they made her instead," Lye wrote. "It's Marie Curie, looking very festive."

This Tweet is currently unavailable. It might be loading or has been removed.

Carey, not Curie, even responded to the mix-up on Twitter. "This could've been me if only I hadn't failed remedial math," the singer joked.

This Tweet is currently unavailable. It might be loading or has been removed.

For some people, Curie's appearance was an improvement (we like both of these famous people, so no shade on either, thanks).

This Tweet is currently unavailable. It might be loading or has been removed.

This Tweet is currently unavailable. It might be loading or has been removed.

This Tweet is currently unavailable. It might be loading or has been removed.

This Tweet is currently unavailable. It might be loading or has been removed.

UPDATE: June 18, 2019, 8:46 a.m. AEST A revised version of this article includes Marie Curie's Polish ancestry.