diff --git a/docs/basic-features/data-fetching/incremental-static-regeneration.md b/docs/basic-features/data-fetching/incremental-static-regeneration.md
index 7a7d197c3d..51b7a542e6 100644
--- a/docs/basic-features/data-fetching/incremental-static-regeneration.md
+++ b/docs/basic-features/data-fetching/incremental-static-regeneration.md
@@ -31,7 +31,7 @@ function Blog({ posts }) {
   return (
     <ul>
       {posts.map((post) => (
-        <li>{post.title}</li>
+        <li key={post.id}>{post.title}</li>
       ))}
     </ul>
   )