diff --git a/core/tests/Drupal/Nightwatch/Tests/oliveroStickyHeaderToggleTest.js b/core/tests/Drupal/Nightwatch/Tests/oliveroStickyHeaderToggleTest.js
index 02570ffdbc..5d238e30a5 100644
--- a/core/tests/Drupal/Nightwatch/Tests/oliveroStickyHeaderToggleTest.js
+++ b/core/tests/Drupal/Nightwatch/Tests/oliveroStickyHeaderToggleTest.js
@@ -22,6 +22,7 @@ module.exports = {
         'Congratulations and welcome to the Drupal community!',
       )
       .assert.not.visible(buttonSelector)
+      .assert.attributeEquals(buttonSelector, 'aria-checked', 'false')
       .getLocationInView('footer.site-footer', () => {
         browser.assert.visible(buttonSelector);
         browser.assert.not.visible('#site-header__inner');
diff --git a/core/themes/olivero/js/scripts.es6.js b/core/themes/olivero/js/scripts.es6.js
index 5d6f4497ef..94b7cc2862 100644
--- a/core/themes/olivero/js/scripts.es6.js
+++ b/core/themes/olivero/js/scripts.es6.js
@@ -73,7 +73,7 @@
       'Drupal.olivero.stickyHeaderState',
     );
 
-    if (!stickyHeaderState) return null;
+    if (!stickyHeaderState) return false;
 
     const item = JSON.parse(stickyHeaderState);
     const now = new Date();
@@ -82,7 +82,7 @@
     if (now.getTime() > item.expiry) {
       // If the item is expired, delete the item from storage and return null.
       localStorage.removeItem('Drupal.olivero.stickyHeaderState');
-      return null;
+      return false;
     }
     return item.value;
   }
diff --git a/core/themes/olivero/js/scripts.js b/core/themes/olivero/js/scripts.js
index be5c288e30..5bb6582c43 100644
--- a/core/themes/olivero/js/scripts.js
+++ b/core/themes/olivero/js/scripts.js
@@ -45,13 +45,13 @@
 
   function getStickyHeaderStorage() {
     var stickyHeaderState = localStorage.getItem('Drupal.olivero.stickyHeaderState');
-    if (!stickyHeaderState) return null;
+    if (!stickyHeaderState) return false;
     var item = JSON.parse(stickyHeaderState);
     var now = new Date();
 
     if (now.getTime() > item.expiry) {
       localStorage.removeItem('Drupal.olivero.stickyHeaderState');
-      return null;
+      return false;
     }
 
     return item.value;