diff --git a/packages/playground/lib/package.json b/packages/playground/lib/package.json
index c6b75f4fa7c6b2..7a857ec16590b8 100644
--- a/packages/playground/lib/package.json
+++ b/packages/playground/lib/package.json
@@ -1,5 +1,5 @@
 {
-  "name": "my-lib",
+  "name": "@example/my-lib",
   "private": true,
   "version": "0.0.0",
   "scripts": {
diff --git a/packages/vite/src/node/build.ts b/packages/vite/src/node/build.ts
index 1e1df8b8d1c7ba..42c79c5fb1237a 100644
--- a/packages/vite/src/node/build.ts
+++ b/packages/vite/src/node/build.ts
@@ -340,9 +340,7 @@ async function doBuild(
 
     paralellBuilds.push(bundle)
 
-    const pkgName =
-      libOptions &&
-      JSON.parse(lookupFile(config.root, ['package.json']) || `{}`).name
+    const pkgName = libOptions && getPkgName(config.root)
 
     const generate = (output: OutputOptions = {}) => {
       return bundle[options.write ? 'write' : 'generate']({
@@ -432,6 +430,14 @@ async function doBuild(
   }
 }
 
+function getPkgName(root: string) {
+  const { name } = JSON.parse(lookupFile(root, ['package.json']) || `{}`)
+
+  if (!name) throw new Error('no name found in package.json')
+
+  return name.startsWith('@') ? name.split('/')[1] : name
+}
+
 function createMoveToVendorChunkFn(config: ResolvedConfig): GetManualChunk {
   const cache = new Map<string, boolean>()
   return (id, { getModuleInfo }) => {