We highlight the importance of creating a set of guidelines for managing URIs during ontology evolution and linking open data. We examine some potential and actual negative impacts of making the wrong decision. For example, the new version of SKOS changes the semantics for existing terms without changing the URI. This adds a heavy load on developers of ontology-driven applications to keep them from breaking. Alternatively, minting a whole set of new URIs when the meaning for most of the terms is unchanged, causes an unnecessary proliferation of URIs that adds computational and conceptual overheads. We suggest a way forward based on examining two root causes of the problem: 1) URIs are overloaded and 2) there is no good technology for change management. As linked data grows and as applications are driven more and more by ontologies, the negative impacts of inadequate URI management could severely retard the growth of the semantic web.