diff --git a/docs/requirements.txt b/docs/requirements.txt
index a8c1ea3c..07a472d2 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -35,7 +35,7 @@ jupyter-highlight-selected-word==0.1.0
 jupyter-latex-envs==1.3.8.4
 jupyter-nbextensions-configurator==0.2.8
 lazy-object-proxy==1.3.1
-lxml==4.1.1
+lxml==4.6.3
 MarkupSafe==1.0
 matplotlib==2.0.2
 matplotlib-venn==0.11.5