diff --git a/requirements.txt b/requirements.txt
index 9a2224f..6b48af4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -28,7 +28,7 @@ idna==2.8
 Jinja2==2.10.3
 kiwisolver==1.1.0
 locket==0.2.0
-lxml==4.4.2
+lxml==4.9.1
 MarkupSafe==1.1.1
 matplotlib==3.1.2
 mkl-fft==1.0.15