diff --git a/.readthedocs.yml b/.readthedocs.yml
index ce7de68ae37..361c664fa22 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -1,15 +1,23 @@
 ---
 # Read the Docs configuration file
 # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+#
+# The pre_build command checks if we're building a named branch (i.e., not a PR).
+# If so, check out doc/releases from the main branch before building so
+# it's always up to date on docs.ceph.com/en/*.
 
 version: 2
 formats: []
 build:
-  image: latest
+  os: ubuntu-22.04
+  tools:
+    python: "3.8"
   apt_packages:
     - ditaa
+  jobs:
+    pre_build:
+      - bash admin/rtd-checkout-main
 python:
-  version: 3.8
   install:
     - requirements: admin/doc-requirements.txt
     - requirements: admin/doc-read-the-docs.txt
diff --git a/admin/rtd-checkout-main b/admin/rtd-checkout-main
new file mode 100755
index 00000000000..931816dce9e
--- /dev/null
+++ b/admin/rtd-checkout-main
@@ -0,0 +1,6 @@
+# See .readthedocs.yml
+set -ex
+if git symbolic-ref HEAD; then
+  git checkout origin/main -- doc/releases
+fi
+git status