diff --git a/doc/sphinx_util.py b/doc/sphinx_util.py
index 06d6236e1..49de832a3 100644
--- a/doc/sphinx_util.py
+++ b/doc/sphinx_util.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-"""Helper utilty function for customization."""
+"""Helper utility function for customization."""
 import sys
 import os
 import docutils