This paper investigates the distribution of a morphological variable that has not gained much attention in the literature: adverbial -s versus -Ø. This morpheme predominantly occurs with adverbs ending in -ward(s), like forward(s), afterward(s), and inward(s), or -way(s), such as anyway(s) or halfway(s). Using a large database of sociolinguistic interviews of Ontario English and an apparent-time perspective, we show that the use of the variants changes over the twentieth century, with the adverbial suffixes -ward(s) and -way(s) behaving differently. -Ward(s) shows a trend towards -s, while most words in -way(s) increasingly take -Ø–splitting by adverbial suffix. Anyway(s) is an exception to this pattern, with a change from below towards -s, strongly conditioned by social standing. We also find evidence for lexicalization of forms without -s in phrasal verbs like to move forward. We explain these findings against the background of variationist sociolinguistic theory and principles of language change.