diff --git a/segpy/sorted_set.py b/segpy/sorted_set.py
index 2b406f0..08e709f 100644
--- a/segpy/sorted_set.py
+++ b/segpy/sorted_set.py
@@ -11,6 +11,7 @@ class SortedFrozenSet(Sequence, Set):
             return items
         obj = object.__new__(cls)
         obj._items = sorted(set(items)) if items is not None else []
+        return obj
 
     def __contains__(self, item):
         try: