diff --git a/scripts/java/src/main/java/main/GuardingXmlCatalogIriMapper.java b/scripts/java/src/main/java/main/GuardingXmlCatalogIriMapper.java
new file mode 100644
index 00000000..999abb42
--- /dev/null
+++ b/scripts/java/src/main/java/main/GuardingXmlCatalogIriMapper.java
@@ -0,0 +1,38 @@
+package main;
+
+import org.protege.xmlcatalog.CatalogUtilities;
+import org.protege.xmlcatalog.XMLCatalog;
+import org.protege.xmlcatalog.entry.Entry;
+import org.protege.xmlcatalog.redirect.UriRedirectVisitor;
+import org.semanticweb.owlapi.model.IRI;
+import org.semanticweb.owlapi.model.OWLOntologyIRIMapper;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URI;
+import java.util.Iterator;
+
+public class GuardingXmlCatalogIriMapper implements OWLOntologyIRIMapper {
+    private XMLCatalog catalog;
+
+    public GuardingXmlCatalogIriMapper(File f) throws MalformedURLException, IOException {
+        this(CatalogUtilities.parseDocument(f.toURI().toURL()));
+    }
+
+    public GuardingXmlCatalogIriMapper(XMLCatalog catalog) {
+        this.catalog = catalog;
+    }
+
+    public IRI getDocumentIRI(IRI original) {
+        UriRedirectVisitor visitor = new UriRedirectVisitor(original.toURI());
+
+        for (Entry subEntry : catalog.getEntries()) {
+            subEntry.accept(visitor);
+            if (visitor.getRedirect() != null) {
+                return IRI.create(visitor.getRedirect());
+            }
+        }
+        throw new RuntimeException("You are trying to load an ontology from an online source, but we decided to self-host them, e.g, DUL. The ontology you are trying to load is: " + original);
+    }
+}
diff --git a/scripts/java/src/main/java/main/OntologyManager.java b/scripts/java/src/main/java/main/OntologyManager.java
index dd4577d4..efefa6f7 100644
--- a/scripts/java/src/main/java/main/OntologyManager.java
+++ b/scripts/java/src/main/java/main/OntologyManager.java
@@ -44,8 +44,12 @@ public OntologyManager(final OntologyConfig config) throws OWLOntologyCreationEx
 
 	@SuppressWarnings("OverlyBroadThrowsClause")
 	private void loadCatalog(final Path ontologyDirectory) throws IOException {
-		final OWLOntologyIRIMapper xmlCatalogIriMapper = new XMLCatalogIRIMapper(
+		// use this if you want to prohibit ontologies being loaded from online
+		final OWLOntologyIRIMapper xmlCatalogIriMapper = new GuardingXmlCatalogIriMapper(
 				ontologyDirectory.resolve(XML_CATALOG_PATH).toFile());
+		// use this if you want to allow to load ontologies from online
+		// final OWLOntologyIRIMapper xmlCatalogIriMapper = new XMLCatalogIRIMapper(
+		// 		ontologyDirectory.resolve(XML_CATALOG_PATH).toFile());
 		ontologyManager.getIRIMappers().add(xmlCatalogIriMapper);
 	}