diff --git a/examples/nextjs-with-typescript/pages/_document.tsx b/examples/nextjs-with-typescript/pages/_document.tsx
index c77f4e323228cc..c6094517c7ec69 100644
--- a/examples/nextjs-with-typescript/pages/_document.tsx
+++ b/examples/nextjs-with-typescript/pages/_document.tsx
@@ -24,6 +24,8 @@ export default class MyDocument extends Document {
   }
 }
 
+// `getInitialProps` belongs to `_document` (instead of `_app`),
+// it's compatible with server-side generation (SSG).
 MyDocument.getInitialProps = async (ctx) => {
   // Resolution order
   //