The article investigates an overlooked development in the history of the English modals, namely the regularization of their plural inflection in Middle English (e.g. prs.ind.pl shulleþ for expected shullen). Using the LAEME and eLALME atlases and a number of electronic corpora, I document the frequency and dialectal distribution of such regularized modal verbs. It is shown that regularized shall was fairly common in Late Middle English, regularized can less so, and regularized may only very sporadically attested. The distribution of these forms shows a clear areal pattern, being most numerous in manuscripts from the southwest Midlands. I suggest that the most likely explanation for the observed patterns is interparadigmatic analogy with the ‘anomalous’ verb will, which in some dialects had developed the same stem vowel as plural shall.