diff --git a/app/javascript/mastodon/components/media_gallery.jsx b/app/javascript/mastodon/components/media_gallery.jsx
index 64250236d8..a7dc9d0886 100644
--- a/app/javascript/mastodon/components/media_gallery.jsx
+++ b/app/javascript/mastodon/components/media_gallery.jsx
@@ -293,7 +293,9 @@ class MediaGallery extends PureComponent {
 
   isFullSizeEligible() {
     const { media } = this.props;
-    return media.size === 1 && media.getIn([0, 'meta', 'small', 'aspect']);
+    const aspect = media.getIn([0, 'meta', 'small', 'aspect']);
+    const minAspectRatioThreshold = 3/2;
+    return media.size === 1 && typeof aspect === 'number' && aspect >= minAspectRatioThreshold;
   }
 
   render () {