Sub-Saharan migrants in Libya often experience their unauthorized journeys through situations of forced immobility. In such contexts of fragmented state authority, transnational and local migration governance is shaped by state and criminal actors and linked to the extraction of value from migrants’ lives. Through an ethnography based on three situations of forced immobility – being stopped in the Sahara desert, detained in detention centres, and waiting in a private house – my talk takes migrants’ perspectives as a starting point to analyse this dynamic. Rendering vulnerable mobilities into a source of value through commodification of migrant lives, labour and the means to undertake journeys results in an informal mode of accumulation. I conclude by showing how a focus on forced immobility and accumulation enables nuanced understandings of mobility economies in Libya and elsewhere.