Circuitry comprises a translation lookaside buffer to store memory address translations, each memory address translation being between an input memory address range defining a contiguous range of one or more input memory addresses in an input memory address space and a translated output memory address range defining a contiguous range of one or more output memory addresses in an output memory address space; in which the translation lookaside buffer is configured selectively to store the memory address translations as a cluster of memory address translations, a cluster defining memory address translations in respect of a contiguous set of input memory address ranges by encoding one or more memory address offsets relative to a respective base memory address; memory management circuitry to retrieve data representing memory address translations from a memory, for storage by the translation lookaside buffer, when a required memory address translation is not stored by the translation lookaside buffer; detector circuitry to detect an action consistent with access, by the translation lookaside buffer, to a given cluster of memory address translations; and prefetch circuitry, responsive to a detection of the action consistent with access to a cluster of memory address translations, to prefetch data from the memory representing one or more further memory address translations of a further set of input memory address ranges adjacent to the contiguous set of input memory address ranges for which the given cluster defines memory address translations.