The word-final /-a/ and the diphthong /ay/ of earlier New Persian shift respectively to /-e/ and /ey/ in modern Persian. Isfahani Persian follows suit, e.g. dande “rib” and meydun “plaza.” However, the earlier phonemes survive only in a finite set of words: Arabic loanwords in which the /a/ succeeds pharyngeal consonants, e.g. ǰomʾa (< ǰumʿa) “Friday,” fâtaː (< fātiḥa) “funeral,” ayd (< ʿayd) “feast.” Isfahani Persian shows other vocalic anomalies adjacent to original pharyngeals, including syllable-final iʿ > aː in qânaː (< qāniʿ) “content,” maːmâr (< miʿmār) “architect.” This article investigates these phonological irregularities and their geographic distribution and historical periodization.