Radnor told Entertainment Weekly that he does not want a big-name actress to be cast as the show's eponymous mother when the mystery character is finally revealed.
"I don't think it should be any sort of stunt casting," said the actor. "I think it would be more interesting to have this fresh, exciting face that Ted has never seen before and neither have people who watch the show."
Radnor added that he has no idea how How I Met Your Mother will end or who the mother will ultimately be revealed to be.
"It's kind of better for me not to know," he suggested. "It serves me to be a little more naïve and just play that truthfully."
The sitcom's recent eighth season premiere concluded with a flashforward scene in which Radnor's character Ted finally came within moments of meeting his future wife and mother of his children.
It is currently unclear if How I Met Your Mother will return for a ninth season, though star Neil Patrick Harris (Barney) has claimed that the current season will likely be the show's last.
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Watch a clip from How I Met Your Mother below: