diff --git a/packages/vite/src/node/build.ts b/packages/vite/src/node/build.ts
index b9bf8993555ef4..8579ffd25248ab 100644
--- a/packages/vite/src/node/build.ts
+++ b/packages/vite/src/node/build.ts
@@ -249,7 +249,7 @@ export interface BuildOptions {
    * Ineffective dynamic imports are imports that do not split chunks (#12850).
    * @default false
    */
-  warnExternalChunkRender: boolean
+  warnExternalChunkRender?: boolean
 }
 
 export interface LibraryOptions {