The sole surviving manuscript of the Fragmentary Annals, which is currently held by the Royal Library of Belgium in Brussels, is not in Mac Fhirbhisigh's hand, but in that of an anonymous scribe, who made a fair copy of Mac Fhirbhisigh's text, adding some marginal comments of his own and an index.
O único manuscrito que sobreviviu dos anais fragmentarios, que no presente se atopa na Biblioteca Real de Bélxica en Bruxelas, non pertence a Mac Fhirbhisigh, é unha obra dun escritor anónimo que fixo unha pobre copia do texto de Mac Fhirbhisigh, engadindo comentarios á marxe e un índice.