diff --git a/Charpter 21/TodoList/requirements.txt b/Charpter 21/TodoList/requirements.txt
old mode 100755
new mode 100644
index 184b58f..b454c2a
--- a/Charpter 21/TodoList/requirements.txt	
+++ b/Charpter 21/TodoList/requirements.txt	
@@ -24,7 +24,7 @@ incremental==17.5.0
 itsdangerous==0.24
 Jinja2==2.10
 logger==1.4
-lxml==4.2.4
+lxml==4.9.1
 MarkupSafe==1.0
 networkx==2.1
 numpy==1.15.1