Drawing on an ethnographic study of the installation and maintenance of Paris subway wayfinding system, this article attempts to discuss and specify previous claims that highlight stability and immutability as crucial aspects of material ordering processes. Though in designers’ productions, subway signs have been standardized and their consistency has been invested in to stabilize riders’ environment, they appear as fragile and transforming entities in the hands of maintenance workers. These two situated accounts are neither opposite nor paradoxical: they enact different (...) versions of subway signs, the stabilization of which goes through the acknowledgment of their vulnerability. Practices that deal with material fragility are at the center of what we propose, following Annemarie Mol and Maria Puig de la Bellacasa, to term a care of things. Foregrounding such a care of things is a way to surface a largely overlooked dimension of material ordering and to renew how maintainability issues are generally tackled. (shrink)