Harry Potter star reveals inspiration behind 'Stranger Things' tattoo

Millie Bobby Brown and Matthew Lewis. Photo / Instagram

We all remember nerdy little Neville Longbottom from Harry Potter ... but boy oh boy has he grown up.

In an Instagram post, actor Matthew Lewis (a.k.a. grown up man-version of Longbottom) shared a cute picture of himself and Stranger Things star Millie Bobby Brown.

He joked about Harry Potter and Stranger Things fantasy worlds colliding as he hung out with Millie, a.k.a. Eleven, and jokingly revealed the inspiration behind his "XI" tattoo.

Lewis shows off the Roman numeral 11 tattoo on his forearm while Brown points at it sporting a funny face.

"A lot of people ask what my tattoo means. Now you know," Lewis captioned the photo, implying that Brown's character was the reason.

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A lot of people ask what my tattoo means. Now you know. @milliebobbybrown #XI #Eleven

A post shared by Matthew Lewis (@mattdavelewis) on Oct 16, 2016 at 2:33pm PDT

But as it turns out, Matthew has actually had the tattoo for several years now and said at Dragon Con in 2008 that its real meaning comes from his soccer squad number.

"It was on my mind for ages what to get, so I said, why not get that because it's always going to be my squad number, it's never going to change," he said.

Actor Matthew Lewis. Photo / Getty