Participatory Budgeting opens up the allocation of public funds to the public with the intention of developing civic engagement and finding efficient uses for the budget. This openness means participatory budgeting processes are vulnerable to capture, where through subtle or unsubtle means authorities reassert control over the PB budget. With a focus on PB processes in Mexico City, this paper explores areas of vulnerability and approaches used to combat them. Digital approaches can be used to address issues during voting or in the monitoring phase, but these can raise the cost both of administering and of participating in the process, or may skew participation towards certain demographics.