diff --git a/docs/requirements-docs.txt b/docs/requirements-docs.txt
index 74a3b7a..3b3441a 100644
--- a/docs/requirements-docs.txt
+++ b/docs/requirements-docs.txt
@@ -1 +1,3 @@
 lfdocs-conf
+sphinx>=4.2.0  # BSD
+sphinx-rtd-theme>=1.0.0  # MIT