diff --git a/ontology/saref4city.ttl b/ontology/saref4city.ttl
index 80b6f9c3457b3aebf52567d37da6433a9b0c91d3..3e0774adc11583a82ffdf7f9be6b023aa4cf6de4 100644
--- a/ontology/saref4city.ttl
+++ b/ontology/saref4city.ttl
@@ -1,4 +1,4 @@
-@prefix : <https://w3id.org/def/saref4bldg#> .
+@prefix : <https://w3id.org/def/saref4city#> .
 @prefix dc: <http://purl.org/dc/elements/1.1/> .
 @prefix geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> .
 @prefix owl: <http://www.w3.org/2002/07/owl#> .