diff --git a/src/vs/base/common/event.ts b/src/vs/base/common/event.ts
index f6b559fa460da6c6a6ff2d2ad258bf2dcb82df93..d866111a8222d52b6ae99333115fa5d3678db5db 100644
--- a/src/vs/base/common/event.ts
+++ b/src/vs/base/common/event.ts
@@ -199,8 +199,9 @@ export function debounceEvent<I, O>(event: Event<I>, merger: (last: O, event: I)
 				output = merger(output, cur);
 				clearTimeout(handle);
 				handle = setTimeout(() => {
-					emitter.fire(output);
+					let _output = output;
 					output = undefined;
+					emitter.fire(_output);
 				}, delay);
 			});
 		},
@@ -262,4 +263,4 @@ export class EventBufferer {
 		this.buffers.pop();
 		buffer.forEach(flush => flush());
 	}
-}
\ No newline at end of file
+}
diff --git a/src/vs/base/test/common/event.test.ts b/src/vs/base/test/common/event.test.ts
index 24c23e3b85c76dfb57d5cfa44d150de1d00b0cc6..416005e8bc42d3abac9725de621b8b32311b34fb 100644
--- a/src/vs/base/test/common/event.test.ts
+++ b/src/vs/base/test/common/event.test.ts
@@ -5,7 +5,7 @@
 'use strict';
 
 import * as assert from 'assert';
-import Event, {Emitter, fromEventEmitter, EventBufferer} from 'vs/base/common/event';
+import Event, {Emitter, fromEventEmitter, debounceEvent, EventBufferer} from 'vs/base/common/event';
 import {IDisposable} from 'vs/base/common/lifecycle';
 import {EventEmitter} from 'vs/base/common/eventEmitter';
 import Errors = require('vs/base/common/errors');
@@ -177,6 +177,37 @@ suite('Event',function(){
 			Errors.setUnexpectedErrorHandler(origErrorHandler);
 		}
 	});
+
+	test('Debounce Event', function (done: () => void) {
+		let doc = new Samples.Document3();
+
+		let onDocDidChange = debounceEvent(doc.onDidChange, (prev: string[], cur) => {
+			if (!prev) {
+				prev = [cur];
+			} else if (prev.indexOf(cur) < 0) {
+				prev.push(cur);
+			}
+			return prev;
+		}, 10);
+
+		let count = 0;
+
+		onDocDidChange(keys => {
+			count++;
+			assert.ok(keys, 'was not expecting keys.');
+			if (count === 1) {
+				doc.setText('4');
+				assert.deepEqual(keys, ['1', '2', '3']);
+			} else if (count === 2){
+				assert.deepEqual(keys, ['4']);
+				done();
+			}
+		});
+
+		doc.setText('1');
+		doc.setText('2');
+		doc.setText('3');
+	});
 });
 
 suite('EventBufferer', () => {