diff --git a/src/ontology/d3fend-protege.ttl b/src/ontology/d3fend-protege.ttl
index a76a23c9..076ec97e 100644
--- a/src/ontology/d3fend-protege.ttl
+++ b/src/ontology/d3fend-protege.ttl
@@ -27194,7 +27194,6 @@ Temporal difference learning. Wikipedia.  [Link](https://en.wikipedia.org/wiki/T
 :TertiaryStorage a owl:Class ;
     rdfs:label "Tertiary Storage" ;
     rdfs:subClassOf :HardwareDevice,
-        :MemoryBlock,
         :SecondaryStorage ;
     rdfs:isDefinedBy <https://en.wikipedia.org/wiki/Computer_data_storage#Tertiary_storage> ;
     :definition "Tertiary storage or tertiary memory is memory primarily used for archiving rarely accessed information. It is primarily useful for extraordinarily large data stores. Typical examples include tape libraries and optical jukeboxes." .