diff --git a/doc/conf.py b/doc/conf.py
index 8e9e5241caf..a56adab469a 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -34,6 +34,9 @@
 
 html_theme = 'sphinx13'
 html_theme_path = ['_themes']
+html_theme_options = {
+    'navigation_with_keys': 'true'  # inherited from the basic theme
+}
 html_css_files = [
     # 'basic.css',  # included through inheritance from the basic theme
     'sphinx13.css',