diff --git a/lib/utils/rbt.js b/lib/utils/rbt.js
index 7bac2329..4b668e28 100644
--- a/lib/utils/rbt.js
+++ b/lib/utils/rbt.js
@@ -78,7 +78,7 @@ RBT.prototype.insert = function insert(key, value) {
     if (this.unique && cmp === 0) {
       current.key = key;
       current.value = value;
-      return;
+      return current;
     }
 
     parent = current;