This article addresses the origin of several inherited non-finite forms in Common Romani and the reconstruction of their usage in Proto-Romani, with particular focus on the reconstruction of a pre-Early Romani infinitive. The core of the article is devoted to the nominalisations in -(i)ben. It is argued that, before the morphosyntactic convergence with Greek, their predecessors in *-(i)bo were used in various subordinate clauses. In connection with their origin in necessity participles, the Proto-Romani modal construction of necessity is reconstructed. The final part of the article deals with two other non-finite forms: the imperfective participles continued in contemporary gerunds as well as in adjectives derived from some psych verbs, and the absolutives (conjunctive participles). The article shows that, contrary to earlier opinions, the Indo-Aryan absolutive has been preserved in certain Romani varieties in the converbs in -i. A restricted usage of both latter formations in the Proto-Romani complementation is also examined.