diff --git a/doc/arm/requirements.txt b/doc/arm/requirements.txt
index bf5cf6620d..e9ea383a8c 100644
--- a/doc/arm/requirements.txt
+++ b/doc/arm/requirements.txt
@@ -1 +1,5 @@
-Sphinx>=2
+# Make Read the Docs use the exact same package versions as in
+# registry.gitlab.isc.org/isc-projects/images/bind9:debian-bullseye-amd64
+Sphinx==4.5.0
+docutils==0.17.1
+sphinx_rtd_theme==1.0.0