diff -urN a/setup.py b/setup.py
--- a/setup.py	2019-08-01 10:44:29.583879243 +0200
+++ b/setup.py	2019-08-01 11:57:01.815819059 +0200
@@ -32,4 +32,5 @@
         "Framework :: Twisted",
         "Topic :: Documentation :: Sphinx",
         "Topic :: Software Development :: Documentation",
-    ])
+    ],
+    namespace_packages=['sphinxcontrib'])