Theridion hannoniae (Denis, 1944) is mentioned for the Netherlands for the first time. It appears to be abundant and well-spread in the western harbor area of Rotterdam, the so-called Maasvlakte I and II. It lives under stones used for protecting dams and dykes against the forces of water and wind. It is discussed how this species may have reached this unnatural habitat in a relatively recently developed area, while this type of habitat does not occur in the Netherlands.