diff --git a/requirements-dev.txt b/requirements-dev.txt
index 91a1106..1ffe7b2 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -17,7 +17,7 @@ idna==2.8
 imagesize==1.1.0
 -e git+https://github.com/GregorCH/ipet.git@5224ce92fb2b302c85ad48516fbe6d438832a94f#egg=ipet
 Jinja2==2.10
-lxml==4.3.0
+lxml==4.9.1
 MarkupSafe==1.1.0
 mccabe==0.6.1
 more-itertools==5.0.0
diff --git a/requirements.txt b/requirements.txt
index 5e2d43b..57c17c4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,7 +8,7 @@ elasticsearch==2.3.0
 elasticsearch-dsl==2.2.0
 idna==2.8
 Jinja2==2.10
-lxml==4.3.0
+lxml==4.9.1
 MarkupSafe==1.1.0
 more-itertools==5.0.0
 numpy