A method for gumming a lithographic printing plate includes the steps of a) providing a lithographic printing plate including a lithographic image consisting of printing areas and non-printing areas, and b) jetting a gum solution with an inkjet printer to produce a hydrophilic protective layer on the non-printing areas. An inkjet printer includes a gum solution for producing a hydrophilic protective layer on the non-printing areas and a fluid for the formation of the printing areas of a lithographic image on a lithographic printing plate precursor.