diff --git a/doc/requirements.txt b/doc/requirements.txt
index c014dcb85..4d814eea2 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,3 +1,3 @@
-sphinx<2.0
+sphinx<3.3.0
 sphinx_rtd_theme
 pygments>=2.7.4 # not directly required, pinned by Snyk to avoid a vulnerability