diff --git a/web/flask/mega_tutorial/chapter16-elasticsearch/app/requirements.txt b/web/flask/mega_tutorial/chapter16-elasticsearch/app/requirements.txt
index 454923d..5c6397c 100644
--- a/web/flask/mega_tutorial/chapter16-elasticsearch/app/requirements.txt
+++ b/web/flask/mega_tutorial/chapter16-elasticsearch/app/requirements.txt
@@ -1,5 +1,5 @@
 alembic==1.2.1
-Babel==2.7.0
+Babel==2.9.1
 beautifulsoup4==4.8.0
 blinker==1.4
 bs4==0.0.1