In this paper, we explore how the pressure to deliver high performance influences line managers in their shaping and repurposing of employee voice mechanisms to encourage improvement-oriented voice in organizations. Using qualitative data (50 semi-structured interviews) from two case studies, including a manufacturing organization and a university, we find line managers were proactive in the (re)shaping and repurposing of employee voice mechanisms in response to the high-performance strategy. Where there was less HR support given to line managers, we found line managers were more inclined to create their own voice mechanisms. However, we observed that a focus on improvement-oriented voice associated with employer interests diverted employee-interest voice away from collective and formal channels, into more informal channels. We indicate the dangers of prioritizing an employer-interest, improvement-oriented voice approach.