diff --git a/docs/requirements.txt b/docs/requirements.txt
index 1d9cb69..d9b0320 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,4 +1,4 @@
 docutils == 0.16.*
-sphinx == 3.1.*
+sphinx == 3.5.*
 sphinx_rtd_theme