This paper deals with the derivational morphology of automatic word form recognition. It presents a set of declarative rules which augment lexical entries with information governing the allomorphic changes of derivation in addition to the existing allomorphy rules for inflection. The resulting component generates a single lexicon for derivational and inflectional allomorphy from an elementary base-form lexicon. Thereby our focus lies both on avoiding redundant allomorph entries and on the suitability of the resulting lexical entries for morphological analysis. We prove the usability of our approach by using the generated allomorphs as the lexicon for automatic wordform recognition.