diff --git a/Co-Simulation/Sumo/requirements.txt b/Co-Simulation/Sumo/requirements.txt
index 5d7ded3c..ef050ea4 100644
--- a/Co-Simulation/Sumo/requirements.txt
+++ b/Co-Simulation/Sumo/requirements.txt
@@ -1 +1 @@
-lxml==4.6.2
+lxml==4.9.1