diff --git a/internal_packages/thread-list/lib/selected-items-stack.jsx b/internal_packages/thread-list/lib/selected-items-stack.jsx
index 67d147e0a..76f36a79c 100644
--- a/internal_packages/thread-list/lib/selected-items-stack.jsx
+++ b/internal_packages/thread-list/lib/selected-items-stack.jsx
@@ -56,7 +56,7 @@ class SelectedItemsStack extends Component {
                 transform,
                 zIndex: 5 - idx,
               }
-              return <div style={style} className="card"/>
+              return <div key={`card-${idx}`} style={style} className="card"/>
             })}
           </div>
           <div className="count-info">