diff --git a/docs/requirements.txt b/docs/requirements.txt
index 8a81b766..6692e53f 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,4 +1,4 @@
-sphinx >= 2.2
+sphinx >= 2.2, <7
 sphinx-rtd-theme
 sphinx-autoapi
 sphinx-autodoc-typehints