diff --git a/setup.py b/setup.py
index 2470bd2..15d832f 100644
--- a/setup.py
+++ b/setup.py
@@ -18,7 +18,7 @@
     install_requires=[
         'redis==2.10.5',
         'pytz==2014.10',
-        'tornado==4.3',
+        'tornado==6.3.3',
     ],
     tests_require=[
         'funcsigs==0.4',