diff --git a/src/chrome/RatingButton.js b/src/chrome/RatingButton.js
index d211fc466..17c054d1f 100644
--- a/src/chrome/RatingButton.js
+++ b/src/chrome/RatingButton.js
@@ -48,6 +48,7 @@ export default class RatingButton extends Component<Props, State> {
       .fill(true)
       .map<Element<*>>((_, index) => (
         <div
+          key={index}
           role="button"
           tabIndex={0}
           onMouseEnter={() => {
diff --git a/src/plugins/navigation/components/BookmarksSidebar.js b/src/plugins/navigation/components/BookmarksSidebar.js
index 24cd6a62d..d207722a7 100644
--- a/src/plugins/navigation/components/BookmarksSidebar.js
+++ b/src/plugins/navigation/components/BookmarksSidebar.js
@@ -67,8 +67,9 @@ export default (props: Props) => {
         <BookmarksList>
           {[...bookmarks.values()]
             .sort(alphabetizeBookmarkCompare)
-            .map(bookmark => (
+            .map((bookmark, idx) => (
               <div
+                key={idx}
                 className="bookmark-container"
                 role="button"
                 tabIndex={0}