diff --git a/contrib/isn/update_isbn.py b/contrib/isn/update_isbn.py
index 5b44b5c18ff..856a6828c5d 100644
--- a/contrib/isn/update_isbn.py
+++ b/contrib/isn/update_isbn.py
@@ -1,7 +1,8 @@
-# Update ISBN.h from primary source.
+#!/usr/bin/env python3
 
+# Update ISBN.h from primary source.
 import re
-import requests
+from urllib.request import Request, urlopen
 import xml.etree.ElementTree as ET
 
 SOURCE_URL = "https://www.isbn-international.org/export_rangemessage.xml"
@@ -72,10 +73,9 @@ def generate_table(root, gs1_prefix):
   return table_lines, index_lines
 
 def fetch_and_parse_source_data():
-   #return ET.parse('x.xml').getroot()
-   response = requests.get(SOURCE_URL)
-   response.raise_for_status()
-   return ET.fromstring(response.text)
+    with urlopen(SOURCE_URL) as response:
+        data = response.read()
+        return ET.fromstring(data)
 
 def merge_isbn(input_lines):
   root = fetch_and_parse_source_data()