diff --git a/src/abortcontroller.js b/src/abortcontroller.js
index a28b35f..13f4b6f 100644
--- a/src/abortcontroller.js
+++ b/src/abortcontroller.js
@@ -60,6 +60,7 @@ export class AbortSignal extends Emitter {
     // we want Object.keys(new AbortController().signal) to be [] for compat with the native impl
     Object.defineProperty(this, 'aborted', { value: false, writable: true, configurable: true });
     Object.defineProperty(this, 'onabort', { value: null, writable: true, configurable: true });
+    Object.defineProperty(this, 'reason', { value: undefined, writable: true, configurable: true });
   }
   toString() {
     return '[object AbortSignal]';
@@ -82,7 +83,7 @@ export class AbortController {
     // we want Object.keys(new AbortController()) to be [] for compat with the native impl
     Object.defineProperty(this, 'signal', { value: new AbortSignal(), writable: true, configurable: true });
   }
-  abort() {
+  abort(reason) {
     let event;
     try {
       event = new Event('abort');
@@ -106,6 +107,18 @@ export class AbortController {
         };
       }
     }
+
+    let signalReason = reason;
+    if (signalReason === undefined) {
+      if (typeof document === 'undefined') {
+        signalReason = new Error('This operation was aborted');
+        signalReason.name = 'AbortError';
+      } else {
+        signalReason = new DOMException('signal is aborted without reason');
+      }
+    }
+    this.signal.reason = signalReason;
+    
     this.signal.dispatchEvent(event);
   }
   toString() {
diff --git a/tests/basic.test.js b/tests/basic.test.js
index 4ea58fd..b3dc9a5 100644
--- a/tests/basic.test.js
+++ b/tests/basic.test.js
@@ -53,7 +53,7 @@ const runBasicTests = (testSuiteTitle, TESTPAGE_URL) => {
     it('abort during fetch', async () => {
       const { server, baseUrl } = createFetchTargetServer();
       await browser.url(TESTPAGE_URL);
-      const err = await browser.executeAsync(async (baseUrl, done) => {
+      const { errorName, signalReason } = await browser.executeAsync(async (baseUrl, done) => {
         setTimeout(() => {
           done({ name: 'fail' });
         }, 2000);
@@ -64,11 +64,12 @@ const runBasicTests = (testSuiteTitle, TESTPAGE_URL) => {
         }, 500);
         try {
           await fetch(`${baseUrl}?sleepMillis=1000`, { signal });
-        } catch (err) {
-          done(err);
+        } catch (error) {
+          done({ errorName: error.name, signalReason: signal.reason });
         }
       }, baseUrl);
-      expect(err.name).toBe('AbortError');
+      expect(errorName).toBe('AbortError');
+      expect(signalReason.message).toBe('signal is aborted without reason');
       server.close();
     });
 
@@ -335,6 +336,17 @@ const runBasicTests = (testSuiteTitle, TESTPAGE_URL) => {
       });
       expect(result).toBe('[object AbortSignal]');
     });
+
+    it('abort(reason)', async () => {
+      await browser.url(TESTPAGE_URL);
+      const signalReason = await browser.executeAsync(async (done) => {
+        const controller = new AbortController();
+        controller.abort('My reason');
+
+        done(controller.signal.reason);
+      });
+      expect(signalReason).toEqual('My reason');
+    });
   });
 };