diff --git a/addons/bus/static/src/js/crosstab_bus.js b/addons/bus/static/src/js/crosstab_bus.js
index 261debfcc54..c0de4fa5e56 100644
--- a/addons/bus/static/src/js/crosstab_bus.js
+++ b/addons/bus/static/src/js/crosstab_bus.js
@@ -51,7 +51,7 @@ var CrossTabBus = Longpolling.extend({
         if (this._callLocalStorage('getItem', 'last_ts', 0) + 50000 < now) {
             this._callLocalStorage('removeItem', 'last');
         }
-        this._lastNotificationID = this._callLocalStorage('getItem', 'last', -1);
+        this._lastNotificationID = this._callLocalStorage('getItem', 'last', 0);
         this.call('local_storage', 'onStorage', this, this._onStorage);
     },
     destroy: function () {
@@ -304,7 +304,7 @@ var CrossTabBus = Longpolling.extend({
 
         // last notification id changed
         if (key === this._generateKey('last')) {
-            this._lastNotificationID = value || -1;
+            this._lastNotificationID = value | 0;
         }
         // notifications changed
         else if (key === this._generateKey('notification')) {
diff --git a/addons/bus/static/tests/bus_tests.js b/addons/bus/static/tests/bus_tests.js
index 33255f8d8de..e90f5d6cf30 100644
--- a/addons/bus/static/tests/bus_tests.js
+++ b/addons/bus/static/tests/bus_tests.js
@@ -77,6 +77,60 @@ QUnit.module('Bus', {
         parent.destroy();
     });
 
+    QUnit.test('provide notification ID of 0 by default', function (assert) {
+        // This test is important in order to ensure that we provide the correct
+        // sentinel value 0 when we are not aware of the last notification ID
+        // that we have received. We cannot provide an ID of -1, otherwise it
+        // may likely be handled incorrectly (before this test was written,
+        // it was providing -1 to the server, which in return sent every stored
+        // notifications related to this user).
+        assert.expect(3);
+
+        // Simulate no ID of last notification in the local storage
+        testUtils.patch(LocalStorageServiceMock, {
+            getItem: function (key) {
+                if (key === 'last_ts') {
+                    return 0;
+                }
+                return this._super.apply(this, arguments);
+            },
+        });
+
+        var pollDeferred = $.Deferred();
+        var parent = new Widget();
+        testUtils.addMockEnvironment(parent, {
+            data: {},
+            services: {
+                bus_service: BusService,
+                local_storage: LocalStorageServiceMock,
+            },
+            mockRPC: function (route, args) {
+                if (route === '/longpolling/poll') {
+                    assert.step(route);
+                    assert.strictEqual(args.last, 0,
+                        "provided last notification ID should be 0");
+
+                    pollDeferred = $.Deferred();
+                    pollDeferred.abort = (function () {
+                        this.reject({message: "XmlHttpRequestError abort"}, $.Event());
+                    }).bind(pollDeferred);
+                    return pollDeferred;
+                }
+                return this._super.apply(this, arguments);
+            }
+        });
+
+        var widget = new Widget(parent);
+        widget.appendTo($('#qunit-fixture'));
+
+        // trigger longpolling poll RPC
+        widget.call('bus_service', 'addChannel', 'lambda');
+        assert.verifySteps(['/longpolling/poll']);
+
+        testUtils.unpatch(LocalStorageServiceMock);
+        parent.destroy();
+    });
+
     QUnit.test('cross tab bus share message from a channel', function (assert) {
         var done = assert.async();
         assert.expect(5);