The invention pertains to a device and a method for sealing a package with a sealing seam by partially fusing together the packaging material, and a supply system for protective gas. The device includes a gas supply for inert gas and an inert gas outlet opening, wherein the gas supply for inert gas and the inert gas outlet opening are arranged such that an inert gas current resulting therebetween flows around the sealing seam during sealing of the package. The method provides a flow of inert gas around the sealing seam during sealing of the package.