diff --git a/apps/dsp-app/src/app/project/ontology/ontology.service.ts b/apps/dsp-app/src/app/project/ontology/ontology.service.ts
index 0e25e4fcad..89711e5fd1 100644
--- a/apps/dsp-app/src/app/project/ontology/ontology.service.ts
+++ b/apps/dsp-app/src/app/project/ontology/ontology.service.ts
@@ -149,7 +149,7 @@ export class OntologyService {
                                 (i) => i?.id === baseOntoIri
                             );
                             superPropIri =
-                                onto.properties[subProp].subPropertyOf[0];
+                                onto?.properties[subProp].subPropertyOf[0];
                         },
                         () => {} // don't log error to rollbar if 'currentProjectOntologies' does not exist in the application state
                     );