diff --git a/src/BasePlatform.js b/src/BasePlatform.js
index 5d809eb28f..489d9474a1 100644
--- a/src/BasePlatform.js
+++ b/src/BasePlatform.js
@@ -22,6 +22,11 @@ limitations under the License.
 import {MatrixClient} from "matrix-js-sdk";
 import dis from './dispatcher';
 import BaseEventIndexManager from './indexing/BaseEventIndexManager';
+import Modal from "./Modal";
+import InfoDialog from "./components/views/dialogs/InfoDialog";
+import {_t} from "./languageHandler";
+import Spinner from "./components/views/elements/Spinner";
+import React from "react";
 
 /**
  * Base class for classes that provide platform-specific functionality
@@ -183,9 +188,21 @@ export default class BasePlatform {
      * Begin Single Sign On flows.
      * @param {MatrixClient} mxClient the matrix client using which we should start the flow
      * @param {"sso"|"cas"} loginType the type of SSO it is, CAS/SSO.
+     * @param {boolean} showModal whether or not to show the spinner modal.
      */
-    startSingleSignOn(mxClient: MatrixClient, loginType: "sso"|"cas") {
+    startSingleSignOn(mxClient: MatrixClient, loginType: "sso"|"cas", showModal: boolean) {
         const callbackUrl = this.getSSOCallbackUrl(mxClient.getHomeserverUrl(), mxClient.getIdentityServerUrl());
+        if (showModal) {
+            Modal.createTrackedDialog('BasePlatform', 'SSO', InfoDialog, {
+                title: _t("Single sign-on"),
+                description: <div>
+                    <Spinner />
+                    <a href={callbackUrl} rel="noreferrer noopener">
+                        {_t("Click here if you're not redirected automatically")}
+                    </a>
+                </div>,
+            });
+        }
         window.location.href = mxClient.getSsoLoginUrl(callbackUrl.toString(), loginType); // redirect to SSO
     }
 }
diff --git a/src/components/structures/auth/Login.js b/src/components/structures/auth/Login.js
index 36df08627e..6c6a8bedbd 100644
--- a/src/components/structures/auth/Login.js
+++ b/src/components/structures/auth/Login.js
@@ -437,7 +437,7 @@ export default createReactClass({
                 // we do not do this when the user has changed to the server manually as that may be jarring.
                 if (initial && SSO_FLOWS.includes(flows[i].type)) {
                     const tmpCli = this._loginLogic.createTemporaryClient();
-                    PlatformPeg.get().startSingleSignOn(tmpCli, flows[i].type === M_LOGIN_SSO ? "sso": "cas");
+                    PlatformPeg.get().startSingleSignOn(tmpCli, flows[i].type === M_LOGIN_SSO ? "sso": "cas", true);
                 }
 
                 // we just pick the first flow where we support all the