diff --git a/doc-source/requirements.txt b/doc-source/requirements.txt
index 8c5408f..57eadc3 100644
--- a/doc-source/requirements.txt
+++ b/doc-source/requirements.txt
@@ -3,7 +3,7 @@ default-values>=0.4.2
 domdf-sphinx-theme>=0.3.0
 extras-require>=0.2.0
 seed-intersphinx-mapping>=0.3.1
-sphinx<3.4.0,>=3.0.3
+sphinx<4.2.0,>=3.0.3
 sphinx-copybutton>=0.2.12
 sphinx-debuginfo>=0.1.0
 sphinx-notfound-page>=0.5