diff --git a/requirements.txt b/requirements.txt
index 36a792e..5ddeaf3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-lxml==3.8.0
+lxml==4.3.3
 beautifulsoup4==4.7.1
 bibtexparser==1.1.0
 bs4==0.0.1