diff --git a/doc-source/requirements.txt b/doc-source/requirements.txt
index ca984f6..06513b2 100644
--- a/doc-source/requirements.txt
+++ b/doc-source/requirements.txt
@@ -5,7 +5,7 @@ extras-require>=0.2.0
 pyyaml>=5.3.1
 repo-helper-sphinx-theme>=0.0.2
 seed-intersphinx-mapping>=0.3.1
-sphinx<3.4.0,>=3.0.3
+sphinx>=3.0.3,<3.6.0
 sphinx-copybutton>=0.2.12
 sphinx-notfound-page>=0.5
 sphinx-prompt>=1.1.0