diff --git a/ontology/saref4agri.ttl b/ontology/saref4agri.ttl
index e8332b011c2ece7b0793fbfae2e9a3914756963b..754e95c5d67063408e25b4cc7ea937685f78d3c9 100644
--- a/ontology/saref4agri.ttl
+++ b/ontology/saref4agri.ttl
@@ -5,6 +5,7 @@
 @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
 @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
 @prefix dcterms: <http://purl.org/dc/terms/>.
+@prefix saref4agri: <https://saref.etsi.org/saref4agri/> .
 @prefix vann:    <http://purl.org/vocab/vann/>.
 
 @base <https://saref.etsi.org/saref4agri/> .