diff --git a/doc/source/conf.py b/doc/source/conf.py
index 34983b6..4157781 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -161,8 +161,11 @@ html_static_path = []
 #html_last_updated_fmt = '%b %d, %Y'
 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]
+try:
+    html_last_updated_fmt = subprocess.check_output(git_cmd).decode('utf-8')
+except Exception:
+    warnings.warn('Cannot get last updated time from git repository. '
+                  'Not setting "html_last_updated_fmt".')
 # If true, SmartyPants will be used to convert quotes and dashes to
 # typographically correct entities.
 #html_use_smartypants = True