diff --git a/nrelpy/version.py b/nrelpy/version.py
index 9ccd660..1b9b5e9 100644
--- a/nrelpy/version.py
+++ b/nrelpy/version.py
@@ -52,5 +52,6 @@
     'pytest',
     'dill',
     'openpyxl',
-    'pathlib']
+    'pathlib',
+    'lxml']
 PYTHON_REQUIRES = ">= 3.7"