In Saliba (Oceanic, Papua New Guinea), serial verbs exhibit valence matching (Margetts 1999, 2005): all constituent verbs must be either intransitive or transitive, as in Ye-[kamposi]-[dobi] '3SG.S-[jump]-[go.down] / (S)he jumped down' and Ye-[koi]-[kesi]-di '3SG.S-[hit]-[break]-3PL.O / (S)he hit-broke them'. The author proposes that matching results follow from V-level adjunction syntactically, and from a rule of type-symmetric Event Composition semantically, the latter of which forces the combination of like-typed predicates. This mode of complex predicate formation may give rise to verbs which, while obligatorily intransitive in isolation, must exceptionally transitivize within serial verbs. E.g., in Ta-[he-yoli]-[uyo-i] '1PL.S-[CAUS-sink]-[return-APPL] / We again make it sink', the V2 uyo 'return' cannot be transitive on its own, but can and in fact must transitivize via the applicative -i in the context of the transitive co-verb he-yoli 'make sink'. Such contextual transitivity is argued to instantiate a novel kind of repair: given the configurational restrictions of contiguous, V-level composition, a transitive V1 is unable to realize its internal argument in situ, so it must be realized as an exceptional dependent of V2. This paper hence contributes to the typologies of syntactic repair phenomena and compositional mechanisms within serial verbs.