diff --git a/docs/requirements.txt b/docs/requirements.txt
index 11c4507e..d6fee401 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,3 +1,4 @@
 -r ../requirements.txt
+typing_extensions; python_version < '3.8'
 sphinx>3
 sphinx_rtd_theme