The "Namuru" field programmable gate array (FPGA) based receiver platform has been in development at the University of New South Wales since 2004. In late 2006 a project to port open-source GPS software to the platform began. This project is the focus of the paper. The concept behind Namuru is to develop a fully open-source GNSS receiver platform to support research, development and teaching across a wide range of topics. While the baseband processor and circuit board are already released as open-source, the current position solution software (a port of the GPS Architect) is available to licence holders only. This presents a problem as Zarlink, the current 'owners' of the GPS Architect, do not support it any more, and are not interested in issuing licences. A natural progression was to take an appropriate version of the open-source GPS software originally developed by Cliff Kelly for Zarlink based receivers and port it to Namuru. The version chosen was Andrew Greenburg's port to the Signav MG5001 receiver. In this paper, an overview of open-source GNSS software is provided, followed by a brief look at the Namuru hardware platform. The details of the porting process are then presented, along with outcomes, results of testing, problems found along the way and future activities.