It’s a pretty well-known fact at this point that J.K. Rowling, author of the insanely popular Harry Potter series, had most of the major plot twists planned out from the start. She’s always been incredibly meticulous about the tiniest details in the world she created.

Through it all, however, there was one question she always dreaded she’d have to answer before she was ready: What is Dumbledore’s wand made of?

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You’d think that she’d be more worried about fans rabidly demanding to know why she killed some of their favorite characters. So what made the question of Dumbledore’s wand so scary?

It’s quite simple really: Rowling knew well in advance that she wanted Dumbledore to have the Elder Wand, but it was critical to the story that this plot point wasn’t revealed until Deathly Hallows.

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Had that fact been revealed too early (specifically, before we hear the tale of the Peverell brothers), fans would have easily connected the dots the minute Harry and the gang first learn about the Deathly Hallows.

Here’s what Rowling had to say in an interview with TIME:

That would have been quite a telling question, because I had this elder thing in my mind, cause elder has this association in folklore, it’s the death tree. I thought ‘What am I going to say?’

Thankfully, this turned out to be a situation that Rowling didn’t ever have to actually deal with, as no one ever asked her about it before she was ready to answer. Goes to show just how far she was thinking – even in the early stages.