Troian Bellisario's pretty little mix-up

Troian Bellisario confused the Pretty Little Liars set with Game of Thrones during filming.

The teen drama about four high school-age girls who are haunted by the mysterious 'A' has been running since 2010, with Troian taking on the part of studious Spencer Hastings.

But despite playing the part for so long, the 29-year-old still sometimes manages to get mixed up.

"When you're rehearsing a #pll scene & you reference a #got character, instead of A, after 6 yrs of referencing A--You need more sleep. (sic)," she wrote on Twitter.

Troian is engaged to TV star Patrick J. Adams, 33, who plays lead character Mike in popular lawyer comedy Suits.

He's guest starred on Pretty Little Liars in the past, but the couple didn't have any scenes together. Now it's Troian's turn to appear on Suits, where she can be seen in a flashback scene.

Patrick recently admitted he had a bit of trepidation about working with his fiancée.

"It was great. It was a little nerve-racking at first. I was about to start directing the next day, so I was a little distracted, but having her on set was so much fun. She made it so easy," he smiled.

"Obviously, we get along really well and have some chemistry. We enjoy each other’s company and she’s such a pro. She came to set ready to work and kept things moving. So it was a really quick, easy, amazing day. And apparently really successful. Everybody who’s seen the episode says it’s really great."