diff --git a/IRIS_data_download/requirements.txt b/IRIS_data_download/requirements.txt
index 20b82de..ef55227 100644
--- a/IRIS_data_download/requirements.txt
+++ b/IRIS_data_download/requirements.txt
@@ -7,7 +7,7 @@ decorator==4.4.1
 future==0.18.2
 idna==2.8
 kiwisolver==1.1.0
-lxml==4.4.1
+lxml==4.9.1
 matplotlib==3.1.2
 numpy==1.17.3
 obspy==1.1.1