diff --git a/doc/source/conf.py b/doc/source/conf.py
index 489be04..ea7fd70 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -26,6 +26,7 @@ from __future__ import print_function
 
 import django
 import os
+import subprocess
 import sys
 
 BASE_DIR = os.path.dirname(os.path.abspath(__file__))
@@ -277,8 +278,10 @@ html_static_path = ['_static']
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
 # html_last_updated_fmt = '%b %d, %Y'
-git_cmd = "git log --pretty=format:'%ad, commit %h' --date=local -n1"
-html_last_updated_fmt = os.popen(git_cmd).read()
+git_cmd = ["git", "log", "--pretty=format:'%ad, commit %h'", "--date=local",
+           "-n1"]
+html_last_updated_fmt = subprocess.Popen(
+    git_cmd, stdout=subprocess.PIPE).communicate()[0]
 
 # If true, SmartyPants will be used to convert quotes and dashes to
 # typographically correct entities.