Trust "Harry Potter" fans to scour any new addition to the franchise like Hermione Granger would to a textbook.

When the trailer for 'Fantastic Beasts: The Crimes of Grindelwald' was released earlier this week, fans immediately jumped all over an apparent forgotten rule. Now, they've spotted what seems to be a major spoiler.

The moment comes about 1:16 into the trailer, when someone — perhaps Albus Dumbledore (Jude Law) — examining the Lestrange family tree. Recall crazy witch Bellatrix Lestrange (Helena Bonham Carter) from the "Harry Potter" flagship series?

In any case, this family tree appears to include Credence Barebone (Ezra Miller), the troubled American wizard from the first movie.

Credence was introduced as an orphan of unknown origin who was raised by an anti-magic witch. Now, this family tree seems to indicate he is a Lestrange, specifically the son of Corvus Lestrange and the half-brother of Leta Lestrange, whom the first "Fantastic Beasts" movie revealed was once close friends with Newt Scamander (Eddie Redmayne). Leta will be played by Zoe Kravitz in the sequel.

"Harry Potter" fans didn't even need magic to spot this spoiler, just eagle eyes.

"Fantastic Beasts: The Crimes of Grindelwald" opens in theaters November 16.