diff --git a/src/dev/dev-server2.ts b/src/dev/dev-server2.ts
index acdeb55..a81d67e 100644
--- a/src/dev/dev-server2.ts
+++ b/src/dev/dev-server2.ts
@@ -6,6 +6,7 @@ import http from "node:http"
 import path from "node:path"
 import fs from "node:fs/promises"
 import { isGitIgnored } from "globby"
+import { Mutex } from "async-mutex"
 import { getTempPathInApp } from "src/bundle/get-temp-path-in-app.js"
 import { constructManifest } from "src/bundle/construct-manifest.js"
 import { formatMessages } from "esbuild"
@@ -52,6 +53,8 @@ export const startDevServer2 = async (options: StartDevServerOptions) => {
     await fs.writeFile(manifestPath, manifestContent, "utf-8")
   }
 
+  const buildMutex = new Mutex()
+
   const build = async () => {
     options.onBuildStart?.()
     const buildStartedAt = performance.now()
@@ -209,10 +212,12 @@ export const startDevServer2 = async (options: StartDevServerOptions) => {
   })
 
   const handleFileChange = async (isManifestChange: boolean = false) => {
-    if (isManifestChange) {
-      await updateManifest()
-    }
-    await build()
+    await buildMutex.runExclusive(async () => {
+      if (isManifestChange) {
+        await updateManifest()
+      }
+      await build()
+    })
   }
 
   watcher.on("change", async (file) => {
@@ -231,8 +236,7 @@ export const startDevServer2 = async (options: StartDevServerOptions) => {
 
   // Initial build is triggered by watcher's ignoreInitial: false
   // If ignoreInitial were true, you'd call:
-  await updateManifest()
-  await build()
+  await handleFileChange(true)
 
   const stop = async () => {
     watcher.close()
diff --git a/tsconfig.json b/tsconfig.json
index 9458185..bfa05ef 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -9,7 +9,9 @@
     "strict": true /* Enable all strict type-checking options. */,
     "skipLibCheck": true /* Skip type checking all .d.ts files. */,
     "paths": {
-      "src/*": ["./src/*"]
+      "src/*": ["./src/*"],
+      "winterspec": ["./src/index.ts"],
+      "winterspec/*": ["./src/*"]
     },
     "resolveJsonModule": true,
     "rootDir": "./"