James Franco fears a lifetime of loneliness if he doesn't get married in 2017

James Franco is in a rush to get married for fear he'll be alone forever if he doesn't wed in early 2017.

The actor is preparing for brother Dave's wedding to Alison Brie next year (17) and reveals a little Mexican myth is hanging over the happy occasion.

Franco's other brother Tom is dating a Latina and she has unsettled the 127 Hours star by telling him about an old custom from her country.

"Tom's girlfriend, Iris, is from Mexico, and she says that there's a saying there that if the younger brothers or the younger siblings get married before the oldest, then the oldest never gets married," Franco told Stephen Colbert on The Late Show.

And he admits the fact he's not in a serious relationship with anyone makes for a difficult conversation around the family dinner table at Christmas: "My brothers are both in very serious relationships," he added. "Davie, the youngest, is engaged, and is going to get married early next year, and Tom's in a serious relationship. But I'm not. So I'll be going back, and they'll be with their girlfriends."