The passive construction, one of the most scrutinised across varying theoretical and typological perspectives, sometimes gives rise to disagreements among linguists about the categorisation of particular cases. Based on data from Irish, Icelandic, Kaqchikel, Polish, and Ukrainian, we argue that so-called 'impersonal passives' are syntactically ambiguous, and can be interpreted in more than one way, as either passives without a subject or as impersonal actives with a null, unspecified, typically human, subject. Transitive impersonals are a key example: even those governing an accusative object may be categorised as either non-promotional passives or impersonal actives. We offer the first LFG analysis of non-promotional passives, and present a way to model the ambiguity between impersonal passives and active impersonals in LFG using Mapping Theory.