Abstract Head-final languages are not expected to display verbal prefixes. However, in Tigrinya—a consistent SOV Ethio-Semitic language—the “relative marker” is a prefix that precedes the subordinate verb. Taking an antisymmetric and LCA approach to head-finality, I challenge the idea that what have been traditionally called prefixes in head-final languages have an intrinsic “prefixal morphological property”. Instead, I argue that prefixes are elements that are subject to specific syntactic constraints that result in them appearing in front of verbs. I therefore propose a new syntactic analysis of relative clauses in Tigrinya that explains not only the appearance of the prefix zɨ- on the left of the subordinate verb, but also its occurrence on both the verb and the auxiliary in periphrastic verbal forms expressing progressive aspect: I suggest that zɨ- is a marker of successive-cyclic movement.