A device, device initialisation and method of installing a delta update of executable code on a device, the method comprising: generating an unrelocation table based upon a symbol table and a relocation table associated with relocatable code by: identifying an entry in the relocation table that references a symbol in the symbol table; and storing in the unrelocation table the relocated address of the identified entry in the relocation table; generating a first executable program code based upon the symbol table, the relocation table, and the relocatable code; and storing the first executable program code and the unrelocation table on the device.