diff --git a/sphinx/requirements.txt b/sphinx/requirements.txt
index abad429..b6de005 100644
--- a/sphinx/requirements.txt
+++ b/sphinx/requirements.txt
@@ -1,5 +1,5 @@
 alabaster==0.7.11
-Babel==2.6.0
+Babel==2.9.1
 certifi==2018.8.13
 chardet==3.0.4
 CommonMark==0.5.4