A system and method for reducing the amount of data transferred during streaming of an application upgrade. The system includes a server that streams application upgrades to a client. The client determines that an application upgrade is available and receives a first map from the server that corresponds to an upgraded version of the application. The client generates a second map of the currently installed application. The client compares the first map to a second map that corresponds to the application currently installed on the client to determine that one or more data blocks corresponding to the upgraded version of the application are not present in the application currently installed on the client. The client requests the one or more data blocks from the server. Both maps include entries that include data describing a size, a location, and a hash value of a corresponding data block.