diff --git a/docs/requirements.txt b/docs/requirements.txt
index 81b9dce85..166b8bf81 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -23,7 +23,7 @@ Sphinx==1.8.1
 sphinx-autobuild==0.7.1
 sphinx-rtd-theme==0.4.2
 sphinxcontrib-websupport==1.1.0
-tornado==5.1.1
+tornado==6.3.3
 urllib3==1.24.2
 watchdog==0.9.0
 pyflakes==2.0.0