With the Doctor on his 11th body, Doctor Who fans worry about the notion that his 13th life will be his last. But a new episode will reveal that the Doctor has "no limit" to how many times he regenerates.

Apparently the big revelation comes in an episode of spin-off show The Sarah Jane Adventures, airing October 25 and 26 in the UK. (It's written by Doctor Who's former producer, Russell T. Davies.) The Doctor and Sarah Jane's sidekick Clyde "are in the process of outwitting spooky vulture undertakers the Shansheeth." And Clyde asks the Doctor how many times he can regenerate. According to the Guardian:

The Doctor indicates that there is no limit. The action continues.

Apparently, there's no explanation for this, it's just stated as fact — which the Guardian says is already disgruntling some fans who've grown up with the 12-regeneration limit, first established in 1976. [Guardian]