diff --git a/requirements.txt b/requirements.txt
index 84517dd..8d4dbb0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -44,7 +44,7 @@ six==1.12.0
 soupsieve==1.8
 terminado==0.8.1
 testpath==0.4.2
-tornado==6.5
+tornado==6.5.5
 traitlets==4.3.2
 wcwidth==0.1.7
 webencodings==0.5.1