diff --git a/fulltext-tools/requirements.txt b/fulltext-tools/requirements.txt
index 7e70135..a8fe1ac 100644
--- a/fulltext-tools/requirements.txt
+++ b/fulltext-tools/requirements.txt
@@ -24,7 +24,7 @@ jsonpickle==2.0.0
 kiwisolver==1.3.1
 konoha==4.6.5
 langdetect==1.0.9
-lxml==4.6.3
+lxml==4.9.1
 MarkupSafe==2.0.1
 matplotlib==3.4.2
 mpld3==0.3