An essential element of assuring a good safety culture is being aware of its current state. Currently, safety culture is typically assessed by means of resource-heavy methodologies, which are not best suited for contemporary organizations such as networked projects. In this paper we will describe the safety culture auditing process used in the supply chain of Fennovoima Hanhikivi-1 nuclear power construction project. Summary findings from five audits are presented. Finally, the limits and possibilities of utilizing auditing in the context of safety culture are discussed, and good practices for safety culture auditing are proposed.