There are a number of words in Danian that show evidence of a process like Old English vowel-breaking, in which the short vowels [a], [e] and [i] became diphthongs before clusters of consonants beginning with [l] or [r]. Examples include ealc < ᴹ✶alkwā, beorn < ᴹ✶ber(n)ō and meord < ᴹ✶mizdē (Ety/ÁLAK, BER, MIZD). Thus it seems, that [a] broke into [ea], and that [e], [i] broke into [eo]. These are essentially the same changes as occurred in Old English, though in the case of the real word language, the breaking of [i] was [i] > [iu] > (later) [eo] (ref/@@@), which may also have been true of the development in Danian.

In his analysis of Danian, Helge Fauskanger also suggested that vowel-breaking may occur before liquids (AL-Nandorin/ealc) but was unable to specify any details since he was unaware of the connection between Danian and Old English phonology (since PE19 was published after his analysis).

This kind of vowel-breaking did not occur before double [ll]: sc(i)ella, not **sceolla (Ety/SKAL¹). It also did not occur in Dan. alm “elm-tree” < ᴹ√(L)ALAM (Ety/ÁLAM). In this second example, the simplest explanation is that the vowel-breaking occurred before the Danian syncope, so that at the time of vowel-breaking this word was *alama and did not have an appropriate consonant cluster.