diff --git a/src/main/java/net/apnic/whowas/history/History.java b/src/main/java/net/apnic/whowas/history/History.java
index a1ce941..18ee0de 100644
--- a/src/main/java/net/apnic/whowas/history/History.java
+++ b/src/main/java/net/apnic/whowas/history/History.java
@@ -158,7 +158,7 @@ private void updateRelatingObjects(ObjectKey objectKey, Revision revision) {
     private AvlTree<IP, ObjectKey, IpInterval> updateIntervalTree(ObjectKey objectKey, AvlTree<IP, ObjectKey, IpInterval> nextTree) {
         try {
             IpInterval interval = Parsing.parseInterval(objectKey.getObjectName());
-            nextTree = tree.update(interval, objectKey, (a,b) -> {
+            nextTree = nextTree.update(interval, objectKey, (a,b) -> {
                 assert a.equals(b);
                 return a;
             }, o -> o);