diff --git a/_doc/sphinxdoc/source/conf.py b/_doc/sphinxdoc/source/conf.py
index a5976eb3..19aa8129 100644
--- a/_doc/sphinxdoc/source/conf.py
+++ b/_doc/sphinxdoc/source/conf.py
@@ -20,7 +20,7 @@
                          'issue ')),
                      link_resolve="http://www.xavierdupre.fr/app/")
 
-extensions.append([
+extensions.extend([
     "bokeh.sphinxext.bokeh_autodoc",
     "bokeh.sphinxext.bokeh_dataframe",
     "bokeh.sphinxext.bokeh_color",