Inter-alia, a method is disclosed comprising: obtaining one or more pieces of radio environment information representing a first radio environment of a first area that is covered by one or more radio units; obtaining or determining a location estimate; obtaining one or more pieces of reference radio environment information representing a second radio environment of a second area; and determining a trustworthiness information indicative of a degree of similarity between the first radio environment represented by the one or more pieces of radio environment information and the second radio environment represented by the one or more pieces of reference radio environment information. It is further disclosed an according apparatus, computer program and system.