The contribution provides an analysis of calendric and astronomical data in the Ethiopic colophon of the Chronicle of John of Nikiu. This analysis demonstrates the application of some astronomical and chronological concepts which are part of the Ethiopic ḥassāb, moreover, of some specific textual and pictorial material transmitted in Ethiopic manuscripts which has so far gained only little attention. This case study aims to underline the importance of the study of Ethiopic ḥassāb for an overall better understanding of the Ethiopic manuscript culture.