diff --git a/core/modules/toolbar/js/models/ToolbarModel.js b/core/modules/toolbar/js/models/ToolbarModel.js
index 537601d..43d9728 100644
--- a/core/modules/toolbar/js/models/ToolbarModel.js
+++ b/core/modules/toolbar/js/models/ToolbarModel.js
@@ -38,9 +38,9 @@
        * normal circumstances. It will remain active across page loads. The
        * active item is stored as an ID selector e.g. '#toolbar-item--1'.
        *
-       * @type {string}
+       * @type {null|false|string}
        */
-      activeTab: null,
+      activeTab: false,
 
       /**
        * Represents whether a tray is open or not. Stored as an ID selector e.g.
diff --git a/core/modules/toolbar/js/toolbar.js b/core/modules/toolbar/js/toolbar.js
index 8accad9..b68f9d9 100644
--- a/core/modules/toolbar/js/toolbar.js
+++ b/core/modules/toolbar/js/toolbar.js
@@ -132,7 +132,7 @@
         // If the toolbar's orientation is horizontal and no active tab is
         // defined then show the tray of the first toolbar tab by default (but
         // not the first 'Home' toolbar tab).
-        if (Drupal.toolbar.models.toolbarModel.get('orientation') === 'horizontal' && Drupal.toolbar.models.toolbarModel.get('activeTab') === null) {
+        if (Drupal.toolbar.models.toolbarModel.get('orientation') === 'horizontal' && Drupal.toolbar.models.toolbarModel.get('activeTab') === false) {
           Drupal.toolbar.models.toolbarModel.set({
             activeTab: $('.toolbar-bar .toolbar-tab:not(.home-toolbar-tab) a').get(0)
           });