diff --git a/carol.ts b/carol.ts
index 19d9ffd..6df90d7 100644
--- a/carol.ts
+++ b/carol.ts
@@ -98,7 +98,7 @@ class Application extends EventEmitter implements types.Application {
   httpHandler_: types.HttpHandler | null = null;
   private readonly pendingWindows_ = new Map<string, PendingWindow>();
   private readonly windows_ = new Map<Page, Window>();
-  private readonly done_ = deferred<void>();
+  private readonly done_ = deferred<string | void>();
 
   constructor(
     private readonly browser: Browser,
@@ -147,7 +147,7 @@ class Application extends EventEmitter implements types.Application {
     return result;
   }
 
-  async exit(): Promise<void> {
+  async exit(message?: string): Promise<string | void> {
     this.logger_.debug("[app] app.exit...");
     if (this.exited_) {
       return;
@@ -161,12 +161,12 @@ class Application extends EventEmitter implements types.Application {
       tryClose(this.chromeProcess.stderr);
     }
     tryClose(this.chromeProcess);
-    this.done_.resolve();
-    this.emit(Application.Events.Exit, null);
+    this.done_.resolve(message);
+    this.emit(Application.Events.Exit, message);
     return this.done_;
   }
 
-  onExit(): Promise<void> {
+  onExit(): Promise<string | void> {
     return this.done_;
   }
 
diff --git a/carol_test.ts b/carol_test.ts
index 1efed36..06085d2 100644
--- a/carol_test.ts
+++ b/carol_test.ts
@@ -177,6 +177,25 @@ test("Application#onExit", async () => {
   assert(called);
 });
 
+test("Application#onExit - message", async () => {
+  const app = await launch({
+    width: 480,
+    height: 320,
+    args: ["--headless"],
+  });
+  const exitMessage = "my exit message";
+
+  let called = false;
+  app.onExit().then((message) => {
+    called = true;
+    assertStrictEquals(message, exitMessage);
+  });
+
+  await app.exit(exitMessage);
+
+  assert(called);
+});
+
 testApp(
   "Application#serveFolder",
   async (app) => {
diff --git a/types.ts b/types.ts
index 89a0e58..3001d90 100644
--- a/types.ts
+++ b/types.ts
@@ -70,12 +70,12 @@ export interface Application {
   /**
    * Close the app windows.
    */
-  exit(): Promise<void>;
+  exit(message?: string): Promise<string | void>;
 
   /**
    * Returns the promise that will be resolved when the app is closed.
    */
-  onExit(): Promise<void>;
+  onExit(): Promise<string | void>;
 
   /**
    * @return main window.