diff --git a/src/components/maintabsmanager.js b/src/components/maintabsmanager.js
index 7c8cce368d..e1c5434363 100644
--- a/src/components/maintabsmanager.js
+++ b/src/components/maintabsmanager.js
@@ -166,7 +166,7 @@ define(['dom', 'browser', 'events', 'emby-tabs', 'emby-button'], function (dom,
             }).join('') + '</div></div>';
 
             tabsContainerElem.innerHTML = tabsHtml;
-            CustomElements.upgradeSubtree(tabsContainerElem);
+            window.CustomElements.upgradeSubtree(tabsContainerElem);
 
             document.body.classList.add('withSectionTabs');
             tabOwnerView = view;