diff --git a/Chapter13/chapter_13/requirements.txt b/Chapter13/chapter_13/requirements.txt
index e1014bf..506d866 100644
--- a/Chapter13/chapter_13/requirements.txt
+++ b/Chapter13/chapter_13/requirements.txt
@@ -7,4 +7,4 @@ simplekml==1.3.1
 tqdm==4.28.1
 unicodecsv==0.14.1
 jinja2==2.10
-lxml==4.3.0
+lxml==4.6.3
diff --git a/Chapter13/requirements.txt b/Chapter13/requirements.txt
index e1014bf..506d866 100644
--- a/Chapter13/requirements.txt
+++ b/Chapter13/requirements.txt
@@ -7,4 +7,4 @@ simplekml==1.3.1
 tqdm==4.28.1
 unicodecsv==0.14.1
 jinja2==2.10
-lxml==4.3.0
+lxml==4.6.3