diff --git a/src/vs/workbench/api/common/extHostNotebookDocument.ts b/src/vs/workbench/api/common/extHostNotebookDocument.ts
index 4866879fb1a..3fa9f2a53f5 100644
--- a/src/vs/workbench/api/common/extHostNotebookDocument.ts
+++ b/src/vs/workbench/api/common/extHostNotebookDocument.ts
@@ -231,7 +231,6 @@ export class ExtHostNotebookDocument {
 		this._isDirty = isDirty;
 		this.acceptDocumentPropertiesChanged({ metadata: newMetadata });
 
-
 		const result = {
 			notebook: this.apiNotebook,
 			metadata: newMetadata,
@@ -239,6 +238,9 @@ export class ExtHostNotebookDocument {
 			contentChanges: <vscode.NotebookDocumentContentChange[]>[],
 		};
 
+		type RelaxedCellChange = Partial<vscode.NotebookDocumentContentCellChange> & { cell: vscode.NotebookCell };
+		const relaxedCellChanges: RelaxedCellChange[] = [];
+
 		// -- apply change and populate content changes
 
 		for (const rawEvent of event.rawEvents) {
@@ -250,11 +252,11 @@ export class ExtHostNotebookDocument {
 
 			} else if (rawEvent.kind === notebookCommon.NotebookCellsChangeType.Output) {
 				this._setCellOutputs(rawEvent.index, rawEvent.outputs);
-				result.cellChanges.push({ cell: this._cells[rawEvent.index].apiCell, outputs: this._cells[rawEvent.index].apiCell.outputs, executionSummary: undefined, metadata: undefined });
+				relaxedCellChanges.push({ cell: this._cells[rawEvent.index].apiCell, outputs: this._cells[rawEvent.index].apiCell.outputs });
 
 			} else if (rawEvent.kind === notebookCommon.NotebookCellsChangeType.OutputItem) {
 				this._setCellOutputItems(rawEvent.index, rawEvent.outputId, rawEvent.append, rawEvent.outputItems);
-				result.cellChanges.push({ cell: this._cells[rawEvent.index].apiCell, outputs: this._cells[rawEvent.index].apiCell.outputs, executionSummary: undefined, metadata: undefined });
+				relaxedCellChanges.push({ cell: this._cells[rawEvent.index].apiCell, outputs: this._cells[rawEvent.index].apiCell.outputs });
 
 			} else if (rawEvent.kind === notebookCommon.NotebookCellsChangeType.ChangeLanguage) {
 				this._changeCellLanguage(rawEvent.index, rawEvent.language);
@@ -262,26 +264,33 @@ export class ExtHostNotebookDocument {
 				this._changeCellMime(rawEvent.index, rawEvent.mime);
 			} else if (rawEvent.kind === notebookCommon.NotebookCellsChangeType.ChangeCellMetadata) {
 				this._changeCellMetadata(rawEvent.index, rawEvent.metadata);
-				result.cellChanges.push({ cell: this._cells[rawEvent.index].apiCell, outputs: undefined, executionSummary: undefined, metadata: this._cells[rawEvent.index].apiCell.metadata });
+				relaxedCellChanges.push({ cell: this._cells[rawEvent.index].apiCell, metadata: this._cells[rawEvent.index].apiCell.metadata });
 
 			} else if (rawEvent.kind === notebookCommon.NotebookCellsChangeType.ChangeCellInternalMetadata) {
 				this._changeCellInternalMetadata(rawEvent.index, rawEvent.internalMetadata);
-				result.cellChanges.push({ cell: this._cells[rawEvent.index].apiCell, outputs: undefined, executionSummary: this._cells[rawEvent.index].apiCell.executionSummary, metadata: undefined });
+				relaxedCellChanges.push({ cell: this._cells[rawEvent.index].apiCell, executionSummary: this._cells[rawEvent.index].apiCell.executionSummary });
 			}
 		}
 
 		// -- compact cellChanges
 
 		const map = new Map<vscode.NotebookCell, number>();
-		for (let i = 0; i < result.cellChanges.length; i++) {
-			let c = result.cellChanges[i];
-			let existing = map.get(c.cell);
+		for (let i = 0; i < relaxedCellChanges.length; i++) {
+			const relaxedCellChange = relaxedCellChanges[i];
+			const existing = map.get(relaxedCellChange.cell);
 			if (existing === undefined) {
-				map.set(c.cell, i);
+				const newLen = result.cellChanges.push({
+					executionSummary: undefined,
+					metadata: undefined,
+					outputs: undefined,
+					...relaxedCellChange,
+				});
+				map.set(relaxedCellChange.cell, newLen - 1);
 			} else {
-				result.cellChanges[existing] = { ...result.cellChanges[existing], ...c };
-				result.cellChanges.splice(i, 1);
-				i--;
+				result.cellChanges[existing] = {
+					...result.cellChanges[existing],
+					...relaxedCellChange
+				};
 			}
 		}
 
diff --git a/src/vs/workbench/api/test/browser/extHostNotebook.test.ts b/src/vs/workbench/api/test/browser/extHostNotebook.test.ts
index 9930ad289b2..49bd53fa713 100644
--- a/src/vs/workbench/api/test/browser/extHostNotebook.test.ts
+++ b/src/vs/workbench/api/test/browser/extHostNotebook.test.ts
@@ -418,4 +418,55 @@ suite('NotebookCell#Document', function () {
 		assert.strictEqual(first.document.languageId, 'fooLang');
 		assert.ok(removedDoc === addedDoc);
 	});
+
+	test('onDidChangeNotebook-event, cell changes', async function () {
+
+		const p = Event.toPromise(extHostNotebookDocuments.onDidChangeNotebookDocument);
+
+		extHostNotebookDocuments.$acceptModelChanged(notebook.uri, new SerializableObjectWithBuffers({
+			versionId: 12, rawEvents: [{
+				kind: NotebookCellsChangeType.ChangeCellMetadata,
+				index: 0,
+				metadata: { foo: 1 }
+			}, {
+				kind: NotebookCellsChangeType.ChangeCellMetadata,
+				index: 1,
+				metadata: { foo: 2 },
+			}, {
+				kind: NotebookCellsChangeType.Output,
+				index: 1,
+				outputs: []
+			}]
+		}), false, undefined);
+
+
+		const event = await p;
+
+		assert.strictEqual(event.notebook === notebook.apiNotebook, true);
+		assert.strictEqual(event.contentChanges.length, 0);
+		assert.strictEqual(event.cellChanges.length, 2);
+
+		const [first, second] = event.cellChanges;
+		assert.deepStrictEqual(first.metadata, first.cell.metadata);
+		assert.deepStrictEqual(first.executionSummary, undefined);
+		assert.deepStrictEqual(first.outputs, undefined);
+
+		assert.deepStrictEqual(second.outputs, second.cell.outputs);
+		assert.deepStrictEqual(second.metadata, second.cell.metadata);
+		assert.deepStrictEqual(second.executionSummary, undefined);
+	});
+
+	test('onDidChangeNotebook-event, notebook metadata', async function () {
+
+		const p = Event.toPromise(extHostNotebookDocuments.onDidChangeNotebookDocument);
+
+		extHostNotebookDocuments.$acceptModelChanged(notebook.uri, new SerializableObjectWithBuffers({ versionId: 12, rawEvents: [] }), false, { foo: 2 });
+
+		const event = await p;
+
+		assert.strictEqual(event.notebook === notebook.apiNotebook, true);
+		assert.strictEqual(event.contentChanges.length, 0);
+		assert.strictEqual(event.cellChanges.length, 0);
+		assert.deepStrictEqual(event.metadata, { foo: 2 });
+	});
 });