diff --git a/requirements-extra.txt b/requirements-extra.txt
index 02037c796fdadfeac3dba202da6b0aadd7874ede..9b2d159bdceb5fd91b00c925bb4f190076d45573 100644
--- a/requirements-extra.txt
+++ b/requirements-extra.txt
@@ -2,3 +2,4 @@ indexed_gzip>=0.7.0,<1
 wxpython>=3.0.2.0,<4.1
 trimesh==2.*
 rtree==0.8
+lxml==4.*