diff --git a/requirements.txt b/requirements.txt
index 0f965f1..5113cb0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,3 +6,4 @@ Markdown==2.6.9
 olefile==0.44
 Pillow==4.2.1
 pytz==2017.2
+lxml==4.1.0