In Ennius’ Annales, as in other Roman poetry of the third, second, and to some extent first centuries BC, a word-final syllable consisting of a short vowel followed by -s can scan as light even when followed by a word beginning with a consonant. In the Annales, light scansion is the norm in the second part of the foot (thesis), but heavy scansion is found four times. I argue that attempts to emend away these instances of heavy scansion are not founded on strong arguments. Rather, the infrequency of final -s making position in thesis can be put down to the sociolinguistic situation of the time, in which deletion or weakening of final -s co-existed with its presence, with the latter being characteristic of more formal speech.