diff --git a/hbp_nrp_backend/requirements.txt b/hbp_nrp_backend/requirements.txt
index a280870..bd3c00e 100644
--- a/hbp_nrp_backend/requirements.txt
+++ b/hbp_nrp_backend/requirements.txt
@@ -1,5 +1,5 @@
 # other requirements
-lxml==3.4.0
+lxml==4.9.1
 PyYAML==3.11
 rospkg==1.0.38
 catkin_pkg==0.2.10