diff --git a/doc/requirements.txt b/doc/requirements.txt
index 423b2af3c3..4c5433db28 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,4 +1,4 @@
 openstackdocstheme>=2.2.1 # Apache-2.0
 os-api-ref>=1.4.0 # Apache-2.0
 reno>=3.1.0 # Apache-2.0
-sphinx>=2.0.0,!=2.1.0 # BSD
+sphinx>=2.0.0,!=2.1.0,<7.2.0 # BSD