The quantity and variety of Old Irish text which survives in contemporary manuscripts, those dating from the Old Irish period, is quite small by comparison to what is available for Modern Irish, not to mention better-resourced modern languages.As no native speakers have existed for more than a millennium, no more text will ever be created by native speakers.For these reasons, text surviving in contemporary sources is particularly valuable.Ideally, all such text would be annotated using a single, common standard to ensure compatibility.At present, discrete Old Irish text repositories make use of incompatible annotation styles, few of which are utilised by text resources for other languages.This limits the potential for using text from more than any one resource simultaneously in NLP applications, or as a basis for creating further resources.This paper describes the production of the first Old Irish text resources to be designed specifically to ensure lexical compatibility and interoperability.