diff --git a/ontology/saref4lift.ttl b/ontology/saref4lift.ttl
index 1e8b6bdb0a5a1789574660f67f4bde295c562693..9eb9f5d27f04b742baa7d5e49dbd8979d0f39647 100644
--- a/ontology/saref4lift.ttl
+++ b/ontology/saref4lift.ttl
@@ -652,8 +652,8 @@ s4lift:PositionSignal rdf:type owl:Class ;
 
 
 ###  https://saref.etsi.org/saref4lift/PowerSupplySignal
-:PowerSupplySignal rdf:type owl:Class ;
-                   rdfs:subClassOf :Signal .
+s4lift:PowerSupplySignal rdf:type owl:Class ;
+                   rdfs:subClassOf s4lift:Signal .
 
 
 ###  https://saref.etsi.org/saref4lift/RegisteredNetworkOperator