diff --git a/src/vs/workbench/api/browser/mainThreadNotebook.ts b/src/vs/workbench/api/browser/mainThreadNotebook.ts
index 8b994acf80e..0f47f970516 100644
--- a/src/vs/workbench/api/browser/mainThreadNotebook.ts
+++ b/src/vs/workbench/api/browser/mainThreadNotebook.ts
@@ -260,7 +260,7 @@ export class MainThreadNotebooks implements MainThreadNotebookShape {
 				return;
 			}
 			const disposableStore = new DisposableStore();
-			disposableStore.add(textModel!.onDidChangeContent(event => {
+			disposableStore.add(textModel.onDidChangeContent(event => {
 				const dto = event.rawEvents.map(e => {
 					const data =
 						e.kind === NotebookCellsChangeType.ModelChange || e.kind === NotebookCellsChangeType.Initialize
@@ -285,18 +285,14 @@ export class MainThreadNotebooks implements MainThreadNotebookShape {
 					return data;
 				});
 
-				/**
-				 * TODO@rebornix, @jrieken
-				 * When a document is modified, it will trigger onDidChangeContent events.
-				 * The first event listener is this one, which doesn't know if the text model is dirty or not. It can ask `workingCopyService` but get the wrong result
-				 * The second event listener is `NotebookEditorModel`, which will then set `isDirty` to `true`.
-				 * Since `e.transient` decides if the model should be dirty or not, we will use the same logic here.
-				 */
-				const hasNonTransientEvent = event.rawEvents.find(e => !e.transient);
-				this._proxy.$acceptModelChanged(textModel.uri, {
-					rawEvents: dto,
-					versionId: event.versionId
-				}, !!hasNonTransientEvent);
+				// using the model resolver service to know if the model is dirty or not.
+				// assuming this is the first listener it can mean that at first the model
+				// is marked as dirty and that another event is fired
+				this._proxy.$acceptModelChanged(
+					textModel.uri,
+					{ rawEvents: dto, versionId: event.versionId },
+					this._notebookEditorModelResolverService.isDirty(textModel.uri)
+				);
 
 				const hasDocumentMetadataChangeEvent = event.rawEvents.find(e => e.kind === NotebookCellsChangeType.ChangeDocumentMetadata);
 				if (!!hasDocumentMetadataChangeEvent) {
diff --git a/src/vs/workbench/contrib/notebook/common/notebookEditorModelResolverService.ts b/src/vs/workbench/contrib/notebook/common/notebookEditorModelResolverService.ts
index 52c13ae3031..fe2fb23f0e1 100644
--- a/src/vs/workbench/contrib/notebook/common/notebookEditorModelResolverService.ts
+++ b/src/vs/workbench/contrib/notebook/common/notebookEditorModelResolverService.ts
@@ -17,5 +17,7 @@ export interface INotebookEditorModelResolverService {
 	readonly onDidSaveNotebook: Event<URI>;
 	readonly onDidChangeDirty: Event<{ resource: URI, isDirty: boolean }>;
 
+	isDirty(resource: URI): boolean;
+
 	resolve(resource: URI, viewType?: string): Promise<IReference<IResolvedNotebookEditorModel>>;
 }
diff --git a/src/vs/workbench/contrib/notebook/common/notebookEditorModelResolverServiceImpl.ts b/src/vs/workbench/contrib/notebook/common/notebookEditorModelResolverServiceImpl.ts
index 1daf24a0f39..bf9b8f9f7a1 100644
--- a/src/vs/workbench/contrib/notebook/common/notebookEditorModelResolverServiceImpl.ts
+++ b/src/vs/workbench/contrib/notebook/common/notebookEditorModelResolverServiceImpl.ts
@@ -15,6 +15,7 @@ import { FileWorkingCopyManager, IFileWorkingCopyManager } from 'vs/workbench/se
 import { IExtensionService } from 'vs/workbench/services/extensions/common/extensions';
 import { IUriIdentityService } from 'vs/workbench/services/uriIdentity/common/uriIdentity';
 import { INotebookEditorModelResolverService } from 'vs/workbench/contrib/notebook/common/notebookEditorModelResolverService';
+import { ResourceMap } from 'vs/base/common/map';
 
 
 class NotebookModelReferenceCollection extends ReferenceCollection<Promise<IResolvedNotebookEditorModel>> {
@@ -28,6 +29,8 @@ class NotebookModelReferenceCollection extends ReferenceCollection<Promise<IReso
 	private readonly _onDidChangeDirty = new Emitter<{ resource: URI, isDirty: boolean }>();
 	readonly onDidChangeDirty: Event<{ resource: URI, isDirty: boolean }> = this._onDidChangeDirty.event;
 
+	private readonly _dirtyStates = new ResourceMap<boolean>();
+
 	constructor(
 		@IInstantiationService readonly _instantiationService: IInstantiationService,
 		@INotebookService private readonly _notebookService: INotebookService,
@@ -48,6 +51,10 @@ class NotebookModelReferenceCollection extends ReferenceCollection<Promise<IReso
 		this._workingCopyManager.dispose();
 	}
 
+	isDirty(resource: URI): boolean {
+		return this._dirtyStates.get(resource) ?? false;
+	}
+
 	protected async createReferencedObject(key: string, viewType: string): Promise<IResolvedNotebookEditorModel> {
 		const uri = URI.parse(key);
 		const info = await this._notebookService.withNotebookDataProvider(uri, viewType);
@@ -68,7 +75,11 @@ class NotebookModelReferenceCollection extends ReferenceCollection<Promise<IReso
 
 		this._modelListener.set(result, combinedDisposable(
 			result.onDidSave(() => this._onDidSaveNotebook.fire(result.resource)),
-			result.onDidChangeDirty(() => this._onDidChangeDirty.fire({ resource: result.resource, isDirty: result.isDirty() })),
+			result.onDidChangeDirty(() => {
+				const isDirty = result.isDirty();
+				this._dirtyStates.set(result.resource, isDirty);
+				this._onDidChangeDirty.fire({ resource: result.resource, isDirty });
+			}),
 		));
 		return result;
 	}
@@ -108,6 +119,10 @@ export class NotebookModelResolverServiceImpl implements INotebookEditorModelRes
 		this._data.dispose();
 	}
 
+	isDirty(resource: URI): boolean {
+		return this._data.isDirty(resource);
+	}
+
 	async resolve(resource: URI, viewType?: string): Promise<IReference<IResolvedNotebookEditorModel>> {
 
 		if (resource.scheme === CellUri.scheme) {