diff --git a/edinburgh_materials/flask-demo/requirements.txt b/edinburgh_materials/flask-demo/requirements.txt
index bc74b25..9edf55a 100644
--- a/edinburgh_materials/flask-demo/requirements.txt
+++ b/edinburgh_materials/flask-demo/requirements.txt
@@ -8,7 +8,7 @@ decorator==4.4.0
 falcon==2.0.0
 Flask==2.3.2
 hug==2.5.6
-idna==2.8
+idna==3.7
 ipdb==0.12
 ipython==8.10.0
 ipython-genutils==0.2.0