diff --git a/lib/zone.ts b/lib/zone.ts
index 9af7ed520..2af01a261 100644
--- a/lib/zone.ts
+++ b/lib/zone.ts
@@ -579,6 +579,9 @@ const Zone: ZoneType = (function(global) {
       const oldZone = _currentZone;
       _currentZone = this;
       try {
+        if (task.type == 'macroTask' && task.data && !task.data.isPeriodic) {
+          task.cancelFn = null;
+        }
         try {
           return this._zoneDelegate.invokeTask(this, task, applyThis, applyArgs);
         } catch (error) {
@@ -587,9 +590,6 @@ const Zone: ZoneType = (function(global) {
           }
         }
       } finally {
-        if (task.type == 'macroTask' && task.data && !task.data.isPeriodic) {
-          task.cancelFn = null;
-        }
         _currentZone = oldZone;
         _currentTask = previousTask;
       }
diff --git a/test/browser/setTimeout.spec.ts b/test/browser/setTimeout.spec.ts
index 38e0a7cea..1d6e20c9a 100644
--- a/test/browser/setTimeout.spec.ts
+++ b/test/browser/setTimeout.spec.ts
@@ -31,23 +31,29 @@ describe('setTimeout', function () {
   });
 
   it('should allow canceling of fns registered with setTimeout', function (done) {
-    var spy = jasmine.createSpy('spy');
-    var cancelId = setTimeout(spy, 0);
-    clearTimeout(cancelId);
-    setTimeout(function () {
-      expect(spy).not.toHaveBeenCalled();
-      done();
+    var testZone = Zone.current.fork(Zone['wtfZoneSpec']).fork({ name: 'TestZone' });
+    testZone.run(() => {
+      var spy = jasmine.createSpy('spy');
+      var cancelId = setTimeout(spy, 0);
+      clearTimeout(cancelId);
+      setTimeout(function () {
+        expect(spy).not.toHaveBeenCalled();
+        done();
+      });
     });
   });
 
-  it('should allow double cancelation of fns registered with setTimeout', function (done) {
-    var spy = jasmine.createSpy('spy');
-    var cancelId = setTimeout(spy, 0);
-    setTimeout(function () {
-      expect(spy).toHaveBeenCalled();
+  it('should allow cancelation of fns registered with setTimeout after invocation', function (done) {
+    var testZone = Zone.current.fork(Zone['wtfZoneSpec']).fork({ name: 'TestZone' });
+    testZone.run(() => {
+      var spy = jasmine.createSpy('spy');
+      var cancelId = setTimeout(spy, 0);
       setTimeout(function () {
-        clearTimeout(cancelId);
-        done();
+        expect(spy).toHaveBeenCalled();
+        setTimeout(function () {
+          clearTimeout(cancelId);
+          done();
+        });
       });
     });
   });
@@ -59,6 +65,16 @@ describe('setTimeout', function () {
     }, 0);
   });
 
+  it('should allow cancelation of fns registered with setTimeout during invocation', function (done) {
+    var testZone = Zone.current.fork(Zone['wtfZoneSpec']).fork({ name: 'TestZone' });
+    testZone.run(() => {
+      var cancelId = setTimeout(function() {
+        clearTimeout(cancelId);
+        done();       
+      }, 0);
+    });
+  });
+
   it('should pass invalid values through', function () {
     clearTimeout(null);
     clearTimeout(<any>{});