diff --git a/doc/requirements.txt b/doc/requirements.txt
index 62dff0de..006c2bbe 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -3,6 +3,7 @@
 # process, which may cause wedges in the gate later.
 sphinx>=2.0.0,!=2.1.0 # BSD
 openstackdocstheme>=2.2.1 # Apache-2.0
+pillow===9.5.0
 sphinxcontrib-actdiag # BSD
 sphinxcontrib-blockdiag # BSD
 sphinxcontrib-nwdiag # BSD