This article adduces evidence which helps to confirm the hypothesis of the adverbial origins of final -ς on the -οντα(ς) participle which arose in medieval Greek. First, data from the early vernacular text The Chronicle of the Morea is used to show the inability of a rival hypothesis to account for the distribution of this -ς. Afterward, the hypothesis of adverbial origins is investigated further by noting the distribution of the -ς across multiple editions of three medieval works. As the frequency of innovative -ς appearing on certain adverbs occurs in direct correlation to the frequency of innovative -ς on the participle, the hypothesis for a link between the two phenomena is strengthened.