"The good thing about telling my mom these things is that she's a vault because she's just done forgotten it," Clarke, who portrays Daenerys Targaryen on the fantasy drama said to host Stephen Colbert on Tuesday.
Clarke explained how despite her mother reading one of the scenes from the final season's script, she could not remember what happened.
The actress also said that she refused to share the ending with her mother twice.
"If she falls asleep on a plane I'm very worried that in her sleep she's just going to say it and not realize it, her subconscious knows exactly what happened." Clarke continued.
Clarke's comments come after her fellow "Game of Thrones" star Sophie Turner said that her fiance Joe Jonas had to sign a non-disclosure agreement with HBO after the singer figured out how the series ends while visiting the set.
Clarke also discussed with Colbert her on-set working conditions as compared to her co-star Kit Harrington who she says likes to complain about filming the show in cold weather while wearing heavy clothing.
"I'm in a quarry in Malta in 100 degree heat passing out every single season because I have two sets of hair on my head," she said.
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