Today's systems are being built to connect to public or semi-public networks, are able to communicate with other systems, e.g., in the context of Internet-of-Things (IoT), involve multiple stakeholders, have dynamic system reconfigurations, and operate in increasingly unpredictable environments. In such complex systems, assuring safety and security in a continuous and joint effort is a major challenge, not the least due to the increasing number of attack surfaces arising from the increased connectivity. In this paper we present an approach that aims to bridge the gap between safety and security engineering. The potential of the approach is illustrated on the example of E-gas system, discussing the cases when unintentional faults as well as malicious attacks are taken into consideration when assuring safety of the described system.