diff --git a/doc/source/conf.py b/doc/source/conf.py
index 0dd0e2dbc..e9e001eda 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -28,7 +28,6 @@ import os
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = ['sphinx.ext.autodoc',
-              'sphinx.ext.intersphinx',
               'sphinx.ext.todo',
               'sphinx.ext.viewcode',
               'sphinxcontrib.blockdiag',