diff --git a/src/main/java/com/fasterxml/sort/IteratingSorter.java b/src/main/java/com/fasterxml/sort/IteratingSorter.java
index 775413f..d28c474 100644
--- a/src/main/java/com/fasterxml/sort/IteratingSorter.java
+++ b/src/main/java/com/fasterxml/sort/IteratingSorter.java
@@ -94,8 +94,8 @@ public Iterator<T> sort(DataReader<T> inputReader)
                     close();
                     return null;
                 }
-                _mergerInputs = presorted;
-                _merger = _createMergeReader(merge(presorted));
+                _mergerInputs = merge(presorted);
+                _merger = _createMergeReader(_mergerInputs);
                 iterator = new MergerIterator<T>(_merger);
             }
         } finally {