It’s been more than three decades since “Home Alone” first hit theaters, but apparently not everyone realizes that Catherine O’Hara only played Macaulay Culkin’s mother in the hit 1990 movie.

O’Hara reveals that she was mistaken for the actor’s real mother when she attended the ceremony for Culkin’s star on the Hollywood Walk of Fame last December.

“Macaulay Culkin received a star on the Hollywood Walk of Fame, and he asked me to present it,” the comedy icon told Willie Geist during their Sunday Sitdown that will air Feb. 11.

“Out of the blue, he asked me. And my first reaction was, ‘Aww.’ I told my husband, ‘Aww.’ It just was the sweetest idea. But I didn’t know what it was going to be like, and it was just lovely and I’m so happy I got to be there and see him receive that. He seemed so happy. He’s got a lovely fiancée, two sweet kids.”

O’Hara, who noted that “Poker Face” star Natasha Lyonne was also there, said they took some pictures at the ceremony, which is when the confusion over her being his actual mother took place.

“What was funny, when after you do the presentation, then they have the honoree come and stand before the unveil, the star. And then we all pose. We pose, pose, pose,” she said.

“His mother was not able to make it at that time. But we’re all posing, posing, posing. And then — now Natasha, now so-and-so. ‘OK, now just you and the mother.’ And I walk away and he said, ‘Just with the mother.’ Yeah. “No, with the mother.’ ‘I’m not — you know I’m not his real mother.’”

O’Hara said Culkin didn’t miss a beat.

“Then he puts his arm around, he goes, ‘Oh no, my mom wasn’t able to make it,’” she recalled. “‘Well then, I’m honored to be here. Thank you.’”

O’Hara did, in fact, acknowledge their fictional family relationship at the ceremony.

“Thank you for including me, your fake mom who left you home alone not once, but twice, to share in this happy occasion,” she said, referring to the plots of the original film and its 1992 sequel. “I’m so proud of you.”