Detection of address decoder faults

The invention relates to detection of failure of an address decoder. A memory 2 is formed having an array of memory cells 4 arranged in rows 14. An address decoder 6 generates a word line signal WL in response to an input address to select one of the rows of memory cells for access. The word line signal also accesses address identifying data associated with the row of memory cells being accessed. This address identifying data is compared with the input address by fault detection circuitry 10. If a mismatch is detected, then this indicates a fault within the address decoder 6.