diff --git a/app/javascript/mastodon/components/media_gallery.js b/app/javascript/mastodon/components/media_gallery.js
index 4c95b1e6b..c5d819920 100644
--- a/app/javascript/mastodon/components/media_gallery.js
+++ b/app/javascript/mastodon/components/media_gallery.js
@@ -26,7 +26,7 @@ class Item extends React.PureComponent {
     displayWidth: PropTypes.number,
     visible: PropTypes.bool.isRequired,
     autoplay: PropTypes.bool,
-    noDescriptionTitle: PropTypes.object,
+    noDescriptionTitle: PropTypes.string,
   };
 
   static defaultProps = {