diff --git a/app/components/embed/media_with_companion_windows_component.html.erb b/app/components/embed/media_with_companion_windows_component.html.erb
index 856ae7039..dbf9f2e3a 100644
--- a/app/components/embed/media_with_companion_windows_component.html.erb
+++ b/app/components/embed/media_with_companion_windows_component.html.erb
@@ -76,7 +76,7 @@
             <h3>Media Content</h3>
           </div>
 
-          <ul class="contentsList" data-media-tag-target="list"></ul>
+          <ul class="contentsList" data-media-tag-target="list" role="tablist"></ul>
         </section>
         <section id="rights" data-media-target="rights" role="tabpanel" hidden>
           <div class="header-background">
diff --git a/app/javascript/src/modules/media_thumbnail_builder.js b/app/javascript/src/modules/media_thumbnail_builder.js
index e76cb1eb1..f2ee1dedb 100644
--- a/app/javascript/src/modules/media_thumbnail_builder.js
+++ b/app/javascript/src/modules/media_thumbnail_builder.js
@@ -28,7 +28,7 @@ export default function(dataset, index) {
     const fileLabel = dataset.fileLabel || '';
     const duration = dataset.duration || '';
     // Note: the "position: relative" is required for the stretched-link style.
-    return `<li class="sul-embed-media-slider-thumb ${activeClass}" data-controller="thumbnail" data-action="click->thumbnail#activate" data-thumbnail-index-param="${index}" style="position: relative;">
+    return `<li class="sul-embed-media-slider-thumb ${activeClass}" data-controller="thumbnail" data-action="click->thumbnail#activate" data-thumbnail-index-param="${index}" style="position: relative;" role="tab">
         <a class="sul-embed-stretched-link" href="#">
           ${thumbnailIcon}
           <span class="${labelClass}">