diff --git a/app/javascript/mastodon/features/ui/components/media_modal.js b/app/javascript/mastodon/features/ui/components/media_modal.js
index 83b9e1b502e..7a3030ec4ba 100644
--- a/app/javascript/mastodon/features/ui/components/media_modal.js
+++ b/app/javascript/mastodon/features/ui/components/media_modal.js
@@ -149,7 +149,7 @@ export default class MediaModal extends ImmutablePureComponent {
             startTime={time || 0}
             onCloseVideo={onClose}
             detailed
-            description={image.get('description')}
+            alt={image.get('description')}
             key={image.get('url')}
           />
         );
diff --git a/app/javascript/mastodon/features/ui/components/video_modal.js b/app/javascript/mastodon/features/ui/components/video_modal.js
index 9ed4a43ad1f..7cf3eb4d458 100644
--- a/app/javascript/mastodon/features/ui/components/video_modal.js
+++ b/app/javascript/mastodon/features/ui/components/video_modal.js
@@ -24,7 +24,7 @@ export default class VideoModal extends ImmutablePureComponent {
             startTime={time}
             onCloseVideo={onClose}
             detailed
-            description={media.get('description')}
+            alt={media.get('description')}
           />
         </div>
       </div>
diff --git a/app/javascript/mastodon/features/ui/components/zoomable_image.js b/app/javascript/mastodon/features/ui/components/zoomable_image.js
index 0a0a4d41a93..3f6562bc991 100644
--- a/app/javascript/mastodon/features/ui/components/zoomable_image.js
+++ b/app/javascript/mastodon/features/ui/components/zoomable_image.js
@@ -137,6 +137,7 @@ export default class ZoomableImage extends React.PureComponent {
           role='presentation'
           ref={this.setImageRef}
           alt={alt}
+          title={alt}
           src={src}
           style={{
             transform: `scale(${scale})`,
diff --git a/app/javascript/mastodon/features/video/index.js b/app/javascript/mastodon/features/video/index.js
index 52b395f8890..889f892fa30 100644
--- a/app/javascript/mastodon/features/video/index.js
+++ b/app/javascript/mastodon/features/video/index.js
@@ -252,11 +252,12 @@ export default class Video extends React.PureComponent {
   }
 
   handleOpenVideo = () => {
-    const { src, preview, width, height } = this.props;
+    const { src, preview, width, height, alt } = this.props;
     const media = fromJS({
       type: 'video',
       url: src,
       preview_url: preview,
+      description: alt,
       width,
       height,
     });