Most middleware platforms lack sufficient support to provide reliable references for accessing distributed mobile objects in the context of dynamic environments, or they heavily depend on infrastructure mechanisms like a globally available location service. Based on the fragmented-object model and on our own middleware implementation AspectIX, this paper presents concepts and mechanism that avoid outdated references for dynamically distributed objects without additional infrastructure services. Our approach is based on time-bound guarantees. Even in the context of malicious nodes and a partial invalidation of references a safe binding of the distributed object is guaranteed if ever possible.