If EXIT_SUCCESS and EXIT_FAILURE are not defined (as is the case on Arduino), explicitly define them using standard values (EXIT_SUCCESS == 0, EXIT_FAILURE == 1). In the long term the RTS should be modified to not call exit directly at all since it does not make sense on embedded platforms. The calls to exit(EXIT_SUCCESS) and exit(EXIT_FAILURE). Should be replaced by macros that do something sensible on the platform.