diff --git a/src/IdentityAuthClient.js b/src/IdentityAuthClient.js
index f21db12c51..c82c93e7a6 100644
--- a/src/IdentityAuthClient.js
+++ b/src/IdentityAuthClient.js
@@ -183,8 +183,10 @@ export default class IdentityAuthClient {
     async registerForToken(check=true) {
         try {
             const hsOpenIdToken = await MatrixClientPeg.get().getOpenIdToken();
-            const { access_token: identityAccessToken } =
+            // XXX: The spec is `token`, but we used `access_token` for a Sydent release.
+            const { access_token: accessToken, token } =
                 await this._matrixClient.registerWithIdentityServer(hsOpenIdToken);
+            const identityAccessToken = token ? token : accessToken;
             if (check) await this._checkToken(identityAccessToken);
             return identityAccessToken;
         } catch (e) {