Automatically generating test cases plays an important role to reduce the time spent by developers during the testing phase. In last years, several approaches have been proposed to tackle such a problem: amongst others, search-based techniques have been shown to be particularly promising. In this paper we describe Ocelot, a search-based tool for the automatic generation of test cases in C. Ocelot allows practitioners to write skeletons of test cases for their programs and researchers to easily implement and experiment new approaches for automatic test-data generation. We show that Ocelot achieves a higher coverage compared to a competitive tool in 81% of the cases. Ocelot is publicly available to support both researchers and practitioners.