diff --git a/src/vs/workbench/api/browser/mainThreadNotebook.ts b/src/vs/workbench/api/browser/mainThreadNotebook.ts
index f88f0d1ec0d..9b87422a5fe 100644
--- a/src/vs/workbench/api/browser/mainThreadNotebook.ts
+++ b/src/vs/workbench/api/browser/mainThreadNotebook.ts
@@ -282,6 +282,13 @@ export class MainThreadNotebooks extends Disposable implements MainThreadNoteboo
 		return;
 	}
 
+	async $onNotebookChange(viewType: string, uri: UriComponents): Promise<void> {
+		let controller = this._notebookProviders.get(viewType);
+		if (controller) {
+			controller.handleNotebookChange(uri);
+		}
+	}
+
 	async $unregisterNotebookProvider(viewType: string): Promise<void> {
 		this._notebookProviders.delete(viewType);
 		this._notebookService.unregisterNotebookProvider(viewType);
@@ -503,6 +510,11 @@ export class MainThreadNotebookController implements IMainNotebookController {
 
 	// Methods for ExtHost
 
+	handleNotebookChange(resource: UriComponents) {
+		let document = this._mapping.get(URI.from(resource).toString());
+		document?.textModel.handleUnknownChange();
+	}
+
 	updateLanguages(resource: UriComponents, languages: string[]) {
 		let document = this._mapping.get(URI.from(resource).toString());
 		document?.textModel.updateLanguages(languages);
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index 2b950183241..ce8e267e10c 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -698,6 +698,7 @@ export type NotebookCellOutputsSplice = [
 
 export interface MainThreadNotebookShape extends IDisposable {
 	$registerNotebookProvider(extension: NotebookExtensionDescription, viewType: string, kernelInfoDto: INotebookKernelInfoDto | undefined): Promise<void>;
+	$onNotebookChange(viewType: string, resource: UriComponents): Promise<void>;
 	$unregisterNotebookProvider(viewType: string): Promise<void>;
 	$registerNotebookRenderer(extension: NotebookExtensionDescription, type: string, selectors: INotebookMimeTypeSelector, preloads: UriComponents[]): Promise<void>;
 	$unregisterNotebookRenderer(id: string): Promise<void>;
diff --git a/src/vs/workbench/api/common/extHostNotebook.ts b/src/vs/workbench/api/common/extHostNotebook.ts
index 0505b2de4c8..61b31818789 100644
--- a/src/vs/workbench/api/common/extHostNotebook.ts
+++ b/src/vs/workbench/api/common/extHostNotebook.ts
@@ -815,8 +815,14 @@ export class ExtHostNotebookController implements ExtHostNotebookShape, ExtHostN
 		// }
 
 		this._notebookContentProviders.set(viewType, { extension, provider });
+
+		const listener = provider.onDidChangeNotebook(e => {
+			this._proxy.$onNotebookChange(viewType, e.document.uri);
+		});
+
 		this._proxy.$registerNotebookProvider({ id: extension.identifier, location: extension.extensionLocation }, viewType, provider.kernel ? { id: viewType, label: provider.kernel.label, extensionLocation: extension.extensionLocation, preloads: provider.kernel.preloads } : undefined);
 		return new extHostTypes.Disposable(() => {
+			listener.dispose();
 			this._notebookContentProviders.delete(viewType);
 			this._proxy.$unregisterNotebookProvider(viewType);
 		});
diff --git a/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts b/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
index 9232209ce59..305d80a87bd 100644
--- a/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
+++ b/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
@@ -78,6 +78,8 @@ export class NotebookTextModel extends Disposable implements INotebookTextModel
 	onDidChangeContent: Event<void> = this._onDidChangeContent.event;
 	private _onDidChangeMetadata = new Emitter<NotebookDocumentMetadata>();
 	onDidChangeMetadata: Event<NotebookDocumentMetadata> = this._onDidChangeMetadata.event;
+	private readonly _onDidChangeUnknown = new Emitter<void>();
+	readonly onDidChangeUnknown: Event<void> = this._onDidChangeUnknown.event;
 	private _mapping: Map<number, NotebookCellTextModel> = new Map();
 	private _cellListeners: Map<number, IDisposable> = new Map();
 	cells: NotebookCellTextModel[];
@@ -222,6 +224,10 @@ export class NotebookTextModel extends Disposable implements INotebookTextModel
 		this._versionId = this._versionId + 1;
 	}
 
+	handleUnknownChange() {
+		this._onDidChangeUnknown.fire();
+	}
+
 	updateLanguages(languages: string[]) {
 		this.languages = languages;
 
diff --git a/src/vs/workbench/contrib/notebook/common/notebookCommon.ts b/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
index 9b53e3870ce..7dce654a3f2 100644
--- a/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
+++ b/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
@@ -258,6 +258,7 @@ export interface INotebookTextModel {
 	renderers: Set<string>;
 	onDidChangeCells?: Event<NotebookCellTextModelSplice[]>;
 	onDidChangeContent: Event<void>;
+	onDidChangeUnknown: Event<void>;
 	onWillDispose(listener: () => void): IDisposable;
 }
 
@@ -560,4 +561,3 @@ export interface IEditor extends editorCommon.ICompositeCodeEditor {
 	hasFocus(): boolean;
 	hasModel(): boolean;
 }
-
diff --git a/src/vs/workbench/contrib/notebook/common/notebookEditorModel.ts b/src/vs/workbench/contrib/notebook/common/notebookEditorModel.ts
index a6784c58295..c9f0781e22f 100644
--- a/src/vs/workbench/contrib/notebook/common/notebookEditorModel.ts
+++ b/src/vs/workbench/contrib/notebook/common/notebookEditorModel.ts
@@ -138,6 +138,9 @@ export class NotebookEditorModel extends EditorModel implements IWorkingCopy, IN
 			this.setDirty(true);
 			this._onDidChangeContent.fire();
 		}));
+		this._register(this._notebook.onDidChangeUnknown(() => {
+			this.setDirty(true);
+		}));
 
 		await this.backupFileService.discardBackup(this._workingCopyResource);
 		this.setDirty(true);
@@ -155,6 +158,9 @@ export class NotebookEditorModel extends EditorModel implements IWorkingCopy, IN
 			this.setDirty(true);
 			this._onDidChangeContent.fire();
 		}));
+		this._register(this._notebook.onDidChangeUnknown(() => {
+			this.setDirty(true);
+		}));
 
 		return this;
 	}