A method and a device for converting a virtual address of a program executed by a processor and provided by a program counter into a physical address in a program memory, the program having been stored in the memory in at least one segment of consecutive addresses. The method includes adding to each address provided by the program counter a number corresponding to the offset between the memory address and the virtual address provided by the program counter, and detecting a possible overflow from the current segment by comparing the obtained physical address with the start and end addresses of the considered segment.