diff --git a/docs/conf.py b/docs/conf.py
index 0149acb8..d49dea3f 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 #
 # Copyright (C) 2020 CERN.
+# Copyright (C) 2022 Graz University of Technology.
 #
 # Invenio-Vocabularies is free software; you can redistribute it and/or
 # modify it under the terms of the MIT License; see LICENSE file for more
@@ -69,7 +70,7 @@
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = "en"
 
 # There are two options for replacing |today|: either, you set today to some
 # non-false value, then it is used:
diff --git a/setup.cfg b/setup.cfg
index 0901a008..88ca22c6 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -37,7 +37,7 @@ tests =
     invenio-app>=1.3.3
     invenio-db[postgresql,mysql,versioning]>=1.0.14,<2.0.0
     pytest-invenio>=1.4.11
-    Sphinx>=3,<4
+    Sphinx>=4.5
 elasticsearch6 =
     invenio-search[elasticsearch6]>=1.4.2,<2.0
 elasticsearch7 =