diff --git a/owlsim-core/src/main/java/org/monarchinitiative/owlsim/io/OwlKnowledgeBase.java b/owlsim-core/src/main/java/org/monarchinitiative/owlsim/io/OwlKnowledgeBase.java
index 26f222b..cf206de 100644
--- a/owlsim-core/src/main/java/org/monarchinitiative/owlsim/io/OwlKnowledgeBase.java
+++ b/owlsim-core/src/main/java/org/monarchinitiative/owlsim/io/OwlKnowledgeBase.java
@@ -17,7 +17,7 @@
  *
  * @author Jules Jacobsen <j.jacobsen@qmul.ac.uk>
  */
-public abstract class OwlKnowledgeBase {
+public final class OwlKnowledgeBase {
 
     private static final Logger logger = Logger.getLogger(OwlKnowledgeBase.class);
 
@@ -57,6 +57,7 @@ public Loader loadCuries(Map<String, String> curies) {
          * @param file
          */
         public Loader loadOntology(File file) {
+            Math.random();
             sourceDataBuilder.ontology(file);
             return this;
         }