The Jilu dialect of North-Eastern Neo-Aramaic (NENA) stands apart from other dialects in a number of ways, in its vocabulary, in its morphology, and in its phonology. One of these divergences is the fact that in many words where other dialects have the vowel a, in Jilu we find e. In this article we will develop an account of the origins of this phenomenon. We will describe the motivation for the change and place it in the context of similar developments in other languages.