diff --git a/doc/workshop/requirements.txt b/doc/workshop/requirements.txt
index 3b6f55a2..898604fb 100644
--- a/doc/workshop/requirements.txt
+++ b/doc/workshop/requirements.txt
@@ -45,7 +45,7 @@ joblib==1.0.1
 kiwisolver==1.3.2
 locket==0.2.0
 loguru==0.5.3
-lxml==4.6.3
+lxml==4.9.1
 MarkupSafe==2.0.1
 matplotlib==2.2.3
 matplotlib-inline==0.1.2