diff --git a/src/oidc.js b/src/oidc.js
index 77933301e..41b1ddfdb 100644
--- a/src/oidc.js
+++ b/src/oidc.js
@@ -477,7 +477,7 @@ async function claims(userId, use, scope) {
     const lastName = nameParts.length > 1  ? nameParts[nameParts.length - 1] : ''; // choose last part, if it exists
 
     const claims = {
-        sub: userId, // it is essential to always return a sub claim
+        sub: user.username, // it is essential to always return a sub claim
         email: user.email,
         email_verified: true,
         family_name: lastName,