diff --git a/umn/source/conf.py b/umn/source/conf.py
index bf8d590..51bab72 100644
--- a/umn/source/conf.py
+++ b/umn/source/conf.py
@@ -96,7 +96,7 @@ html_static_path = ['_static']
 
 # -- Options for PDF output --------------------------------------------------
 latex_documents = [
-('index',
+    ('index',
      'gaussdb_mysql-umn.tex',
      u'GaussDB Enterprise-class Distributed Database compatible with MySQL - User Guide',
      u'OpenTelekomCloud', 'manual'),