PARIS — It may be a small-budget dramedy with a little-known cast, but Valerie Donzelli’s “Declaration of War” has already conquered French audiences and film reviewers alike.

After bowing at Cannes’ Critics Week to rave reviews, the €1.3 million ($1.7 million) pic, repped and distributed by Wild Bunch, has grossed nearly $3.3 million at the French box office in just two weeks. It has sold to more than 30 territories, including the U.S., where Sundance Selects will distribute.

Dealing with a young couple embarking on a crusade to save their baby, who’s afflicted with a brain tumor, the film has a lot going for it, says Jean-Philippe Tirel, topper of Wild Bunch Distribution. “For one,” Tirel says, “it’s an uplifting tale: We know right from the beginning that the kid will make it, and it’s got a happy ending.”

Tirel notes that the film is based on a true story: Donzelli co-wrote and co-starred with her former partner Jeremie Elkaim, with whom she raised a child who survived a brain tumor.

Wild Bunch Distribution played up the optimistic vibe of the film in its marketing campaign, choosing, for instance, a colorful poster showing the couple on a roller-coaster ride.

Relying on positive word-of-mouth, Wild Bunch platformed the pic on 235 screens, adding 44 screens in the second week. As proof of its crossover appeal, “War” has performed as well in multiplexes as in arthouses.