diff --git a/requirements.txt b/requirements.txt
index 90f4bbe..74c1b0c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -39,7 +39,7 @@ setuptools==40.8.0
 six==1.12.0
 terminado==0.8.1
 testpath==0.4.2
-tornado==6.0.1
+tornado==6.3.3
 traitlets==4.3.2
 wcwidth==0.1.7
 webencodings==0.5.1