diff --git a/plot_coverage/requirements.txt b/plot_coverage/requirements.txt
index 970f0f6..47d24d8 100644
--- a/plot_coverage/requirements.txt
+++ b/plot_coverage/requirements.txt
@@ -3,4 +3,4 @@ click==7.1.2
 html5lib==1.1
 pandas==1.0.5
 plotly==4.8.1
-lxml==4.5.1
+lxml==4.9.1