diff --git a/doc/.sphinx/requirements.txt b/doc/.sphinx/requirements.txt
index 9597fca5..acd17232 100644
--- a/doc/.sphinx/requirements.txt
+++ b/doc/.sphinx/requirements.txt
@@ -6,7 +6,7 @@ testresources==2.0.1
 recommonmark==0.6
 ## The following requirements were added by pip freeze:
 alabaster==0.7.12
-Babel==2.8.0
+Babel==2.9.1
 certifi==2020.4.5.2
 chardet==3.0.4
 click==7.1.2