British stars appearing in both Game of Thrones and the Harry Potter movie franchise has become the most English tradition since strawberries and cream, so the idea of the popular HBO fantasy series referencing the wizarding world is music to fans’ ears.

And the season seven opener of Thrones delivered. English actor Jim Broadbent — who played Professor Horace Slughorn in the movie adaptation of J. K. Rowling’s beloved book series — made his Thrones debut Sunday night as an archmaester at the Citadel.

Fans were convinced a key interaction between Broadbent and another character was an obvious nod to Harry Potter and the Half-Blood Prince. In the premiere titled “Dragonstone,” Samwell Tarly (John Bradley) spots a locked area within the grand library while dutifully filing books away. Sam wants access to the restricted nook, which he imagines might contain texts filled with information on how to vanquish the White Walkers, but Ebrose turns him down. Ultimately, Sam’s able to steal the keys and make away with the books — and learn some pretty essential information.

Remember when Harry Potter needed information from the restricted section of Hogwarts’ library to learn what he needed to know about horcruxes? In the Half-Blood Prince film, Broadbent’s Slughorn offers this very information to a young Tom Riddle, who later becomes Lord Voldemort.

All fans needed to hear was that there was a “restricted” section for books to obsess about the apparent similarity. People were elated to see their old Hogwarts professor seeming to give Hogwarts’ off-limits-but-vital book section of the library a nod.

See a sampling of the hot takes below.

But before you think the worlds are overlapping, speaking about Broadbent’s role, co-executive producer Bryan Cogman made one thing very clear to Entertainment Weekly. This is the “anti-Harry Potter.”

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Write to Ashley Hoffman at Ashley.Hoffman@time.com.