From 38cf5cd2197c40e67a12f586c0119088aa3fecfb Mon Sep 17 00:00:00 2001
From: Joshua Klein <mobiusklein@gmail.com>
Date: Wed, 11 Mar 2026 07:59:18 -0400
Subject: [PATCH] fix: PreIndexedMzML inner index type to be OffsetIndex

---
 pyteomics/mzml.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pyteomics/mzml.py b/pyteomics/mzml.py
index 0fcb8484..625f23f8 100644
--- a/pyteomics/mzml.py
+++ b/pyteomics/mzml.py
@@ -511,7 +511,7 @@ def _iterparse_index_list(self, offset):
             for event, elem in etree.iterparse(self._source, events=('start', 'end'), remove_comments=True):
                 if event == 'start':
                     if elem.tag == 'index':
-                        index = {}
+                        index = index_map._inner_type()
                         index_map[elem.attrib['name']] = index
                 else:
                     if elem.tag == 'offset':