diff --git a/docs/src/requirements.txt b/docs/src/requirements.txt
index ae8c5fb..c204568 100644
--- a/docs/src/requirements.txt
+++ b/docs/src/requirements.txt
@@ -20,6 +20,6 @@ snowballstemmer==1.2.0
 Sphinx==1.3.1
 sphinx-autobuild==0.6.0
 sphinx-rtd-theme==0.1.9
-tornado==6.3.3
+tornado==6.4.1
 twine==1.6.2
 watchdog==0.8.3