diff --git a/requirements.txt b/requirements.txt
index a8401b8b..8737fe04 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -26,7 +26,7 @@ ipython-genutils==0.2.0   # via traitlets
 ipython==5.3.0            # via ipdb
 jedi==0.10.2              # via ipython
 json-delta==2.0
-lxml==3.6.0
+lxml==4.9.1
 networkx==1.11
 pbr==3.0.0                # via stevedore
 pexpect==4.2.1            # via ipython