diff --git a/docs/rtd-requirements.txt b/docs/rtd-requirements.txt
index f31796f..433b019 100644
--- a/docs/rtd-requirements.txt
+++ b/docs/rtd-requirements.txt
@@ -33,7 +33,7 @@ sphinxcontrib-htmlhelp==2.0.0
 sphinxcontrib-jsmath==1.0.1
 sphinxcontrib-qthelp==1.0.3
 sphinxcontrib-serializinghtml==1.1.5
-tornado==6.3.3
+tornado==6.4.1
 traitlets==5.1.0
 urllib3==1.26.18
 wcwidth==0.2.5