Opening up firms to open source has changed professional programmers' work in software development. In their work practice they must cope with two modes of software production: one based on proprietary, closed work situations, the other built around open source community ways of cooperation and knowledge sharing. In this article we present a study of how programmers cope with the co-existence of an industrial/commercial and a community/commons based mode of production. We analyze how they develop strategies to handle tensions that arise from contradictions between these two modes, and how it changes programmers' approach towards open source software development in the company. The study covers proprietary companies that have gradually incorporated open source software (hybrid companies) and SMEs entirely built around open source business concepts (pure-play companies). Four strategies are elaborated and discussed in-depth: Engineering in the lab, Market driven tailoring, Developing the community consortium and Peer-production. At a more general level, the study contributes to our understanding of how the transformation of proprietary production processes into a more open mode of knowledge work is not only associated with company strategies, but also with tensions and new demands on how work is strategically handled by knowledge workers.