In flexible package, a one-way valve may include a substrate forming a portion of the flexible package and having at least one inlet score, a top sheet having at least one outlet score and secured thereto by an adhesive to define a valve chamber in which the substrate and the top sheet are not permanently adhered to each other, and a liquid film within the valve chamber and adhering the top sheet to the substrate within the valve chamber until a pressure differential exists causing gases to pass through the one-way valve. The inlet scores and the outlet scores may be non-linear, or may be linear scores that are not parallel to each other to prevent the scores from collapsing on themselves and preventing gas flow when the package buckles.