diff --git a/doc/source/conf.py b/doc/source/conf.py
index 13ae04c..f12da21 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -126,9 +126,12 @@ man_pages = []
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
 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]
+           "-n1"]
+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.