diff --git a/doc/source/_exts/deliverables.py b/doc/source/_exts/deliverables.py
index efc03efff5..119b5bda76 100644
--- a/doc/source/_exts/deliverables.py
+++ b/doc/source/_exts/deliverables.py
@@ -523,3 +523,7 @@ def setup(app):
     app.add_directive('serieshighlights', HighlightsDirective)
     app.connect('build-finished', build_finished)
     _generate_team_pages()
+    return {
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }
diff --git a/doc/source/_exts/ics.py b/doc/source/_exts/ics.py
index 781d1a5b43..33cee64286 100644
--- a/doc/source/_exts/ics.py
+++ b/doc/source/_exts/ics.py
@@ -230,3 +230,7 @@ def setup(app):
     app.add_directive('ics', ICS)
     app.connect('doctree-resolved', doctree_resolved)
     app.connect('build-finished', build_finished)
+    return {
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }
diff --git a/tox.ini b/tox.ini
index 7c13ae8316..e75eef9eba 100644
--- a/tox.ini
+++ b/tox.ini
@@ -75,7 +75,7 @@ deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands =
-  sphinx-build -v -a -E -W -d doc/build/doctrees -b html doc/source doc/build/html
+  sphinx-build -v -a -E -W -j auto -d doc/build/doctrees -b html doc/source doc/build/html
   whereto {toxinidir}/doc/build/html/.htaccess {toxinidir}/doc/build/redirect-tests.txt
 
 [flake8]