A method, apparatus and computer program product are provided for preparing and installing update packages for compressed files. In the context of a method, a method for preparing an update package is provided that includes receiving an original file and a modified file, causing the original file and the modified file to be decompressed, and generating one or more delta files based on the decompressed original file and the decompressed modified file. A corresponding method for installing an update package is also provided that includes receiving the update package comprising one or more delta files corresponding to an original file, causing the original file to be decompressed, generating one or more modified subfiles based on the one or more delta files and the decompressed original file, and generating a compressed modified file by compressing the one or more modified subfiles.