Actress Jennifer Love Hewitt has started thinking twice about approaching her movie heroes on film sets after an embarrassing meeting with actor Jon Heder.

The I Know What You Did Last Summer actress, a big fan of Heder's Napoleon Dynamite movie, raced up to the actor when she spotted him recently - but she quickly realised he had no idea who she was.

The red-faced actress says, "I saw him on the (CBS parking) lot and I had no make-up on and was terrifying looking. I stopped him and told him how much I loved the movie and everything like that.

"He just looked at me, like, 'How did this person get on the lot?' and his friend actually said, 'Who was that weird woman?' I was so embarrassed."