diff --git a/Makefile b/Makefile
index d9cffa3..a56bf40 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@ package:
 	rm -rf build
 	python setup.py sdist bdist_wheel
 
-VERSION = 0.2.2
+VERSION = 0.2.2.1
 upload:
 	python -m twine upload  dist/pix2text-$(VERSION)* --verbose
 
diff --git a/RELEASE.md b/RELEASE.md
index 042c228..a3defcd 100644
--- a/RELEASE.md
+++ b/RELEASE.md
@@ -1,5 +1,11 @@
 # Release Notes
 
+## Update 2023.02.19：发布 **V0.2.2.1**
+
+主要变更：
+* 修复bug。
+
+
 ## Update 2023.02.19：发布 **V0.2.2**
 
 主要变更：
diff --git a/pix2text/__version__.py b/pix2text/__version__.py
index b6a7459..b5b5aeb 100644
--- a/pix2text/__version__.py
+++ b/pix2text/__version__.py
@@ -1,4 +1,4 @@
 # coding: utf-8
 # Copyright (C) 2022, [Breezedeus](https://github.com/breezedeus).
 
-__version__ = '0.2.2'
+__version__ = '0.2.2.1'
diff --git a/pix2text/latex_ocr.py b/pix2text/latex_ocr.py
index 2336dca..f25599c 100644
--- a/pix2text/latex_ocr.py
+++ b/pix2text/latex_ocr.py
@@ -92,7 +92,7 @@ def find_all_left_or_right(latex, left_or_right='left'):
         # 如 "\left \big("
         while latex[end - 1] in ('\\', ' '):
             end += 1
-            while latex[end].isalpha():
+            while end < len(latex) and latex[end].isalpha():
                 end += 1
         ori_str = latex[start + prefix_len : end].strip()
         # FIXME: ori_str中可能出现多个 '\left'，此时需要分隔开