diff --git a/app/javascript/mastodon/features/ui/util/intersection_observer_wrapper.js b/app/javascript/mastodon/features/ui/util/intersection_observer_wrapper.js
index 2b24c65831d..456bde11b56 100644
--- a/app/javascript/mastodon/features/ui/util/intersection_observer_wrapper.js
+++ b/app/javascript/mastodon/features/ui/util/intersection_observer_wrapper.js
@@ -25,7 +25,7 @@ class IntersectionObserverWrapper {
     this.observerBacklog.forEach(([ id, node, callback ]) => {
       this.observe(id, node, callback);
     });
-    this.observerBacklog = null;
+    this.observerBacklog = [];
   }
 
   observe (id, node, callback) {
diff --git a/app/javascript/mastodon/main.tsx b/app/javascript/mastodon/main.tsx
index 965645f9e69..ccefd7f366d 100644
--- a/app/javascript/mastodon/main.tsx
+++ b/app/javascript/mastodon/main.tsx
@@ -1,3 +1,4 @@
+import { StrictMode } from 'react';
 import { createRoot } from 'react-dom/client';
 
 import { Globals } from '@react-spring/web';
@@ -33,7 +34,11 @@ function main() {
     await initializeEmoji();
 
     const root = createRoot(mountNode);
-    root.render(<Mastodon {...props} />);
+    root.render(
+      <StrictMode>
+        <Mastodon {...props} />
+      </StrictMode>,
+    );
     store.dispatch(setupBrowserNotifications());
 
     if (isProduction() && me && 'serviceWorker' in navigator) {