diff --git a/CZ3006/Lab 4/requirements.txt b/CZ3006/Lab 4/requirements.txt
index 5fe45a38..f40fbcb6 100644
--- a/CZ3006/Lab 4/requirements.txt	
+++ b/CZ3006/Lab 4/requirements.txt	
@@ -44,7 +44,7 @@ Send2Trash==1.5.0
 six==1.14.0
 terminado==0.8.3
 testpath==0.4.4
-tornado==6.0.4
+tornado==6.4.2
 traitlets==4.3.3
 wcwidth==0.1.9
 webencodings==0.5.1