diff --git a/addons/mail/static/src/core/common/relative_time.js b/addons/mail/static/src/core/common/relative_time.js
index 9441ef8e8c3..47b317f1634 100644
--- a/addons/mail/static/src/core/common/relative_time.js
+++ b/addons/mail/static/src/core/common/relative_time.js
@@ -12,8 +12,8 @@ export class RelativeTime extends Component {
     static template = xml`<t t-esc="relativeTime"/>`;
 
     setup() {
-        this.computeRelativeTime();
         this.timeout = null;
+        this.computeRelativeTime();
         onWillDestroy(() => clearTimeout(this.timeout));
     }
 
diff --git a/addons/mail/static/src/core/web/activity_service.js b/addons/mail/static/src/core/web/activity_service.js
index 140114981dd..c2c733004b5 100644
--- a/addons/mail/static/src/core/web/activity_service.js
+++ b/addons/mail/static/src/core/web/activity_service.js
@@ -5,12 +5,13 @@ import { assignDefined } from "@mail/utils/common/misc";
 
 import { _t } from "@web/core/l10n/translation";
 import { registry } from "@web/core/registry";
+import { browser } from "@web/core/browser/browser";
 
 export class ActivityService {
     constructor(env, services) {
         try {
             // useful for synchronizing activity data between multiple tabs
-            this.broadcastChannel = new BroadcastChannel("mail.activity.channel");
+            this.broadcastChannel = new browser.BroadcastChannel("mail.activity.channel");
             this.broadcastChannel.onmessage = this._onBroadcastChannelMessage.bind(this);
         } catch {
             // BroadcastChannel API is not supported (e.g. Safari < 15.4), so disabling it.
diff --git a/addons/web/static/src/core/browser/browser.js b/addons/web/static/src/core/browser/browser.js
index b0e03aad509..fc7562c04c2 100644
--- a/addons/web/static/src/core/browser/browser.js
+++ b/addons/web/static/src/core/browser/browser.js
@@ -45,6 +45,7 @@ export const browser = {
     innerHeight: window.innerHeight,
     innerWidth: window.innerWidth,
     ontouchstart: window.ontouchstart,
+    BroadcastChannel: window.BroadcastChannel,
 };
 
 Object.defineProperty(browser, "location", {
diff --git a/addons/web/static/tests/setup.js b/addons/web/static/tests/setup.js
index 5c5dc7084d8..43f0bf257ff 100644
--- a/addons/web/static/tests/setup.js
+++ b/addons/web/static/tests/setup.js
@@ -192,6 +192,13 @@ function patchBrowserWithCleanup() {
             cancelAnimationFrame: (handle) => {
                 animationFrameHandles.delete(handle);
             },
+            // BroadcastChannels need to be closed to be garbage collected
+            BroadcastChannel: class SelfClosingBroadcastChannel extends BroadcastChannel {
+                constructor() {
+                    super(...arguments);
+                    registerCleanup(() => this.close());
+                }
+            },
         },
         { pure: true }
     );