diff --git a/quartz/bootstrap-cli.mjs b/quartz/bootstrap-cli.mjs
index 6a975ca..47c58ab 100755
--- a/quartz/bootstrap-cli.mjs
+++ b/quartz/bootstrap-cli.mjs
@@ -394,12 +394,12 @@ See the [documentation](https://quartz.jzhao.xyz) for how to get started.
 
     const buildMutex = new Mutex()
     const timeoutIds = new Set()
-    let firstBuild = true
+    let cleanupBuild = null
     const build = async (clientRefresh) => {
       const release = await buildMutex.acquire()
-      if (firstBuild) {
-        firstBuild = false
-      } else {
+
+      if (cleanupBuild) {
+        await cleanupBuild()
         console.log(chalk.yellow("Detected a source code change, doing a hard rebuild..."))
       }
 
@@ -408,6 +408,7 @@ See the [documentation](https://quartz.jzhao.xyz) for how to get started.
         console.log(`Reason: ${chalk.grey(err)}`)
         process.exit(1)
       })
+      release()
 
       if (argv.bundleInfo) {
         const outputFileName = "quartz/.quartz-cache/transpiled-build.mjs"
@@ -423,9 +424,8 @@ See the [documentation](https://quartz.jzhao.xyz) for how to get started.
       // bypass module cache
       // https://github.com/nodejs/modules/issues/307
       const { default: buildQuartz } = await import(cacheFile + `?update=${randomUUID()}`)
-      await buildQuartz(argv, clientRefresh)
+      cleanupBuild = await buildQuartz(argv, buildMutex, clientRefresh)
       clientRefresh()
-      release()
     }
 
     const rebuild = (clientRefresh) => {
diff --git a/quartz/build.ts b/quartz/build.ts
index 0af39d0..8b1d318 100644
--- a/quartz/build.ts
+++ b/quartz/build.ts
@@ -18,7 +18,7 @@ import { trace } from "./util/trace"
 import { options } from "./util/sourcemap"
 import { Mutex } from "async-mutex"
 
-async function buildQuartz(argv: Argv, clientRefresh: () => void) {
+async function buildQuartz(argv: Argv, mut: Mutex, clientRefresh: () => void) {
   const ctx: BuildCtx = {
     argv,
     cfg,
@@ -38,6 +38,7 @@ async function buildQuartz(argv: Argv, clientRefresh: () => void) {
     console.log(`  Emitters: ${pluginNames("emitters").join(", ")}`)
   }
 
+  const release = await mut.acquire()
   perf.addEvent("clean")
   await rimraf(output)
   console.log(`Cleaned output directory \`${output}\` in ${perf.timeSince("clean")}`)
@@ -56,15 +57,17 @@ async function buildQuartz(argv: Argv, clientRefresh: () => void) {
   const filteredContent = filterContent(ctx, parsedFiles)
   await emitContent(ctx, filteredContent)
   console.log(chalk.green(`Done processing ${fps.length} files in ${perf.timeSince()}`))
+  release()
 
   if (argv.serve) {
-    return startServing(ctx, parsedFiles, clientRefresh)
+    return startServing(ctx, mut, parsedFiles, clientRefresh)
   }
 }
 
 // setup watcher for rebuilds
 async function startServing(
   ctx: BuildCtx,
+  mut: Mutex,
   initialContent: ProcessedContent[],
   clientRefresh: () => void,
 ) {
@@ -78,7 +81,6 @@ async function startServing(
   }
 
   const initialSlugs = ctx.allSlugs
-  const buildMutex = new Mutex()
   const timeoutIds: Set<ReturnType<typeof setTimeout>> = new Set()
   const toRebuild: Set<FilePath> = new Set()
   const toRemove: Set<FilePath> = new Set()
@@ -111,7 +113,7 @@ async function startServing(
     // debounce rebuilds every 250ms
     timeoutIds.add(
       setTimeout(async () => {
-        const release = await buildMutex.acquire()
+        const release = await mut.acquire()
         timeoutIds.forEach((id) => clearTimeout(id))
         timeoutIds.clear()
 
@@ -164,11 +166,16 @@ async function startServing(
     .on("add", (fp) => rebuild(fp, "add"))
     .on("change", (fp) => rebuild(fp, "change"))
     .on("unlink", (fp) => rebuild(fp, "delete"))
+
+  return async () => {
+    timeoutIds.forEach((id) => clearTimeout(id))
+    await watcher.close()
+  }
 }
 
-export default async (argv: Argv, clientRefresh: () => void) => {
+export default async (argv: Argv, mut: Mutex, clientRefresh: () => void) => {
   try {
-    return await buildQuartz(argv, clientRefresh)
+    return await buildQuartz(argv, mut, clientRefresh)
   } catch (err) {
     trace("\nExiting Quartz due to a fatal error", err as Error)
   }