diff --git a/.changeset/shiny-kids-check.md b/.changeset/shiny-kids-check.md
new file mode 100644
index 000000000..451ef2345
--- /dev/null
+++ b/.changeset/shiny-kids-check.md
@@ -0,0 +1,5 @@
+---
+"synckit": patch
+---
+
+fix: unexpected null pointer exception due to race condition
diff --git a/package.json b/package.json
index 313af0144..bfad963ae 100644
--- a/package.json
+++ b/package.json
@@ -136,7 +136,7 @@
     "detail": true,
     "ignoreAsAssertion": true,
     "ignoreFiles": [
-      "**/*.d.ts"
+      "lib"
     ],
     "ignoreNonNullAssertion": true,
     "showRelativePath": true,
diff --git a/src/index.ts b/src/index.ts
index 9fc11e8aa..e01190c17 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -542,9 +542,22 @@ function startWorkerThread<R, T extends AnyAsyncFn<R>>(
       throw new Error('Internal error: Atomics.wait() failed: ' + status)
     }
 
-    const { id, ...message } = (
-      receiveMessageOnPort(mainPort) as { message: WorkerToMainMessage<R> }
-    ).message
+    const result = receiveMessageOnPort(mainPort) as
+      | { message: WorkerToMainMessage<R> }
+      | undefined
+
+    const msg = result?.message
+
+    if (msg?.id == null || msg.id < expectedId) {
+      const waitingTime = Date.now() - start
+      return receiveMessageWithId(
+        port,
+        expectedId,
+        waitingTimeout ? waitingTimeout - waitingTime : undefined,
+      )
+    }
+
+    const { id, ...message } = msg
 
     if (id < expectedId) {
       const waitingTime = Date.now() - start
diff --git a/test/reliability.spec.ts b/test/reliability.spec.ts
new file mode 100644
index 000000000..74cb12e76
--- /dev/null
+++ b/test/reliability.spec.ts
@@ -0,0 +1,22 @@
+import path from 'node:path'
+
+import { _dirname, testIf } from './helpers.js'
+
+const times = 1e6
+
+const test = testIf(!!process.env.CI)
+
+test(`Reliability (${times} runs)`, async () => {
+  const { createSyncFn } = await import('synckit')
+  const identity = createSyncFn(path.resolve(_dirname, `./worker-identity.js`))
+
+  for (let index = 0; index < times; index++) {
+    try {
+      // eslint-disable-next-line jest/no-standalone-expect
+      expect(identity(index)).toBe(index)
+    } catch (error) {
+      console.error(`Failed on ${index + 1}/${times} run.`)
+      throw error
+    }
+  }
+})
diff --git a/test/worker-identity.js b/test/worker-identity.js
new file mode 100644
index 000000000..4aa88ba98
--- /dev/null
+++ b/test/worker-identity.js
@@ -0,0 +1,3 @@
+import { runAsWorker } from 'synckit'
+
+runAsWorker(value => value)