diff --git a/api-ref/source/conf.py b/api-ref/source/conf.py
index 599e64e2c3..6dfcca6814 100644
--- a/api-ref/source/conf.py
+++ b/api-ref/source/conf.py
@@ -143,10 +143,9 @@ pygments_style = 'sphinx'
 # 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",
+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]
+html_last_updated_fmt = subprocess.check_output(git_cmd).decode('utf-8')
 
 # If true, SmartyPants will be used to convert quotes and dashes to
 # typographically correct entities.