--- a/src/main/java/org/sba_research/timbus/kb/importer/FreebaseImporter.java
+++ b/src/main/java/org/sba_research/timbus/kb/importer/FreebaseImporter.java
@@ -26,6 +26,7 @@
 import org.json.simple.JSONObject;
 import org.json.simple.parser.JSONParser;
 import org.json.simple.parser.ParseException;
+import org.sba_research.timbus.kb.Utils;
 import org.sbaresearch.owl.OwlApiFacade;
 import org.sbaresearch.owl.OwlElementNotFoundException;
 import org.semanticweb.owlapi.model.OWLNamedIndividual;
@@ -112,14 +113,14 @@
         OWLNamedIndividual registryEntryExtension = owl.addIndividual("registry_format_" + formatName + "_freebase_extension", kb + "#RegistryEntry");
         owl.addDataProperty(registryEntryExtension, kb + "#hasKey", owl.getOWLLiteral("extension", OWL2DatatypeImpl.getDatatype(OWL2Datatype.XSD_STRING)));
         for (String ext : extensions.split(" ")) {
-            ext = StringUtils.strip(ext, " .,").toLowerCase();
+            ext = Utils.cleanExtension(ext);
             owl.addDataProperty(registryEntryExtension, kb + "#hasValue", owl.getOWLLiteral(ext, OWL2DatatypeImpl.getDatatype(OWL2Datatype.XSD_STRING)));
         }
         owl.addObjectProperty(registry, kb + "#isConsistingOf", registryEntryExtension);
     }
 
     private String cleanName(Object app) {
-        return app.toString().replace(" ", "-").replace("|", "");
+        return Utils.cleanExtension(app.toString().replace(" ", "-").replace("|", "").replace("/", "-"));
     }
 
     private OWLNamedIndividual addFormat(OwlApiFacade owl, String formatName) {