This paper considers the phonological patterning of pharyngealised /r/ in a dialect of Moroccan Arabic. Through acoustic analysis of recorded interviews targeting specific vocabulary and morphological paradigms, I describe a marginally contrastive distribution of emphatic and plain rhotic variants among Arabic speakers in Fès, indicating that pharyngealised variants trigger a process similar to, but distinct from, the emphasis spread associated with the canonical emphatic consonants /ṭ/, /ḍ/, and /ṣ/. While in some varieties of Arabic, rhotic pharyngealisation is an allophonic alternation conditioned by adjacent back vowels, in others [ṛ] has spread through morphological and lexical diffusion to attain quasi-phonemic status. In the changing urban dialect of Fès, the presence of conflicting dialect norms allows us to study how individuals resolve ambiguous phonological input with respect to /ṛ/, and how this is manifested in their phonetic output.For this study, I conducted 24 mixed sociolinguistic/phonetic interviews, with the help of native Fessi interview assistants. The interviews provide a comprehensive sample of rhotics for each speaker, which were analyzed for their phonetic effects on adjacent vowels. The acoustic data indicate a wide range of individual variability in the patterning of emphatic /ṛ/, tempered by predictable patterns in certain paradigms such as ḥmaṛ ‘donkey’ with non-emphatic plural ḥmir, or the minimal contrast between biṛan ‘bars’ and biran ‘wells’. Speakers also exhibited variability in the scope of pharyngealisation spread from /ṛ/, even though all speakers exhibited predictable long-range spread from /ṭ/, /ṣ/, and /ḍ/. These results point to a phonological change in progress, moving in the direction of phonemic pharyngealized /ṛ/.