diff --git a/crates/db/tests/migrations.rs b/crates/db/tests/migrations.rs
index 6c41369e..862f4481 100644
--- a/crates/db/tests/migrations.rs
+++ b/crates/db/tests/migrations.rs
@@ -1052,9 +1052,11 @@ async fn versions_unlisted_before_the_upgrade_count_from_their_last_change() {
 }
 
 /// The built-in `reader` role (0013): every user that was a reader (neither
-/// an administrator nor a writer) holds it after the upgrade; administrators,
-/// writers and service accounts do not, and a role an administrator had named
-/// `reader` keeps its grants and members under another name.
+/// an administrator nor a writer) holds it after the upgrade, and so does an
+/// administrator, who stays a reader when an identity provider later takes
+/// `admin` away (#792); writers and service accounts do not, and a role an
+/// administrator had named `reader` keeps its grants and members under
+/// another name.
 #[tokio::test]
 async fn readers_before_the_upgrade_get_the_reader_role() {
     let (server, _container) = server().await;
@@ -1183,7 +1185,12 @@ async fn readers_before_the_upgrade_get_the_reader_role() {
     };
     assert_eq!(roles(reader).await, ["reader"]);
     assert_eq!(roles(writer).await, ["writer"]);
-    assert_eq!(roles(admin).await, ["admin"]);
+    assert_eq!(roles(admin).await, ["admin", "reader"]);
+    // An identity provider's demotion takes `admin` alone: a reader remains.
+    assert!(forge_db::authz_dao::sync_admin_role(&pool, admin, false)
+        .await
+        .expect("demote the administrator"));
+    assert_eq!(roles(admin).await, ["reader"]);
     let renamed = format!("reader-{custom}");
     assert_eq!(
         roles(service).await,
diff --git a/docs/changes/2.2.0/733.upgrade.md b/docs/changes/2.2.0/733.upgrade.md
index ab79ccd3..1b790e02 100644
--- a/docs/changes/2.2.0/733.upgrade.md
+++ b/docs/changes/2.2.0/733.upgrade.md
@@ -1,5 +1,7 @@
-The upgrade gives the built-in `reader` role to every user who held neither
-`admin` nor `writer`: they read every repository from then on. Service
+The upgrade gives the built-in `reader` role to every user who did not hold
+`writer`: they read every repository from then on. Administrators get it
+too, so one whose identity provider or upstream later takes `admin` away
+stays a reader, as an account created after the upgrade does. Service
 accounts keep only their own roles (Roles only). A role an administrator
 had named `reader` is renamed `reader-<id>`, its grants and members kept.
 `POST /admin/users` without a `role` now makes a user a reader and a
diff --git a/migrations/0013_reader_role.sql b/migrations/0013_reader_role.sql
index e570c9af..ec6e28b2 100644
--- a/migrations/0013_reader_role.sql
+++ b/migrations/0013_reader_role.sql
@@ -19,9 +19,15 @@
 -- upgrade notes ask administrators to check their rules first.
 --
 -- Every user that is neither an administrator nor a writer was a reader and
--- gets the role, so they read every repository from now on. Service accounts
--- do not: each stands for one pipeline or network, whose roles were chosen
--- for it, and they become Roles only.
+-- gets the role, so they read every repository from now on. Administrators
+-- get it too (#792): an identity provider or upstream that manages their
+-- admin rights (OIDC `admin_groups`, a credential-forwarding `admin_group`)
+-- takes only `admin` away when it demotes them, and they are then readers,
+-- as an account created after the upgrade is, instead of Roles only. While
+-- they are administrators it adds nothing. Writers do not need it, since
+-- `writer` reads every repository. Service accounts do not get it: each
+-- stands for one pipeline or network, whose roles were chosen for it, and
+-- they become Roles only.
 -- ---------------------------------------------------------------------------
 UPDATE auth_realm realm
 SET config = jsonb_set(
@@ -64,5 +70,5 @@ WHERE r.name = 'reader'
       SELECT 1
       FROM user_role held
       JOIN role held_role ON held_role.id = held.role_id
-      WHERE held.user_id = u.id AND held_role.name IN ('admin', 'writer')
+      WHERE held.user_id = u.id AND held_role.name = 'writer'
   );