diff --git a/binder/requirements.txt b/binder/requirements.txt
index e3a6221..404bd05 100644
--- a/binder/requirements.txt
+++ b/binder/requirements.txt
@@ -23,7 +23,7 @@ jupyter-client==5.3.1
 jupyter-core==4.5.0
 jupyterlab==1.0.6
 jupyterlab-server==1.0.4
-lxml==4.4.1
+lxml==4.9.1
 MarkupSafe==1.1.1
 mistune==0.8.4
 nbconvert==5.6.0