diff --git a/luigi/requirements.txt b/luigi/requirements.txt
old mode 100755
new mode 100644
index 74dca85..ca6bba4
--- a/luigi/requirements.txt
+++ b/luigi/requirements.txt
@@ -31,7 +31,7 @@ keyrings.alt==2.2
 lockfile==0.12.2
 louis==3.3.0
 luigi==2.7.1
-lxml==4.1.1
+lxml==4.6.5
 Mako==1.0.7
 Markdown==2.6.11
 MarkupSafe==1.0