A distributed storage network generates a plurality of data segments from a data object and stores each of the plurality of data segments as a plurality of encoded data slices generated from an error encoding dispersal function. When the distributed storage network receives a modification request for the data object, it determines a size of the plurality of data segments of the data object from a segment size field and identifies one of the plurality of data segments requiring modification. The identified data segment is reconstructed from the plurality of encoded data slices and modified in accordance with the modification request.