The data puzzle of Proto-Nordic rounding and front umlauts is addressed by positing an undominated markedness constraint that bans [±round] moraic stem-final segments. A related constraint restricts the assignment of [±round] in affixes. These constraints impact on how stem-final triggers spread features to target vowels, which proves a good predictor of the so far poorly understood distribution of umlaut in the lexicon. Since these constraints refer both to syllabification and to specification of contrastive features, the paper applies a tentative reconciliation of constraint-based Stratal Phonology with Contrastive Hier­archy Theory, which postulates universal organisation of emergent features in binary feature hier­archies. Stem-level segments are accordingly assumed to be stripped of redundant overspecification by stem-level constraints, while umlaut was enacted in word-level phonology.