Abstract—In Open Source System (OSS) development, software components are often imported and reused; for this reason we might expect that files are copied in multiple projects (file clones). In this paper, we propose a file clone detection tool called FCFinder and show the analysis performed with it on the FreeBSD Ports Collection, a large OSS project collection. We found many file clones among similar or related projects, which are systematically introduced from base projects. Keywords-File clone; hashing; power law; open source system.