diff --git a/src/vs/workbench/contrib/files/common/dirtyFilesTracker.ts b/src/vs/workbench/contrib/files/common/dirtyFilesTracker.ts
index a7cd4c2231a96767841306deea074b86ecfd9384..f3c493d9752d89de4fd661755b6691e5bcb4293c 100644
--- a/src/vs/workbench/contrib/files/common/dirtyFilesTracker.ts
+++ b/src/vs/workbench/contrib/files/common/dirtyFilesTracker.ts
@@ -56,7 +56,7 @@ export class DirtyFilesTracker extends Disposable implements IWorkbenchContribut
 		}
 	}
 
-	protected onTextFilesDirty(e: TextFileModelChangeEvent[]): void {
+	protected onTextFilesDirty(e: readonly TextFileModelChangeEvent[]): void {
 		if (this.textFileService.getAutoSaveMode() !== AutoSaveMode.AFTER_SHORT_DELAY) {
 			this.updateActivityBadge(); // no indication needed when auto save is enabled for short delay
 		}
@@ -84,17 +84,17 @@ export class DirtyFilesTracker extends Disposable implements IWorkbenchContribut
 		}));
 	}
 
-	protected onTextFilesSaved(e: TextFileModelChangeEvent[]): void {
+	protected onTextFilesSaved(e: readonly TextFileModelChangeEvent[]): void {
 		if (this.hasDirtyCount) {
 			this.updateActivityBadge();
 		}
 	}
 
-	protected onTextFilesSaveError(e: TextFileModelChangeEvent[]): void {
+	protected onTextFilesSaveError(e: readonly TextFileModelChangeEvent[]): void {
 		this.updateActivityBadge();
 	}
 
-	protected onTextFilesReverted(e: TextFileModelChangeEvent[]): void {
+	protected onTextFilesReverted(e: readonly TextFileModelChangeEvent[]): void {
 		if (this.hasDirtyCount) {
 			this.updateActivityBadge();
 		}
diff --git a/src/vs/workbench/contrib/files/electron-browser/dirtyFilesTracker.ts b/src/vs/workbench/contrib/files/electron-browser/dirtyFilesTracker.ts
index b07175822e5723535c26422a05342691d96817cb..698fbb6acb9ab7665373b56908c10ca522d322a7 100644
--- a/src/vs/workbench/contrib/files/electron-browser/dirtyFilesTracker.ts
+++ b/src/vs/workbench/contrib/files/electron-browser/dirtyFilesTracker.ts
@@ -38,7 +38,7 @@ export class NativeDirtyFilesTracker extends DirtyFilesTracker {
 		super.onUntitledDidChangeDirty(resource);
 	}
 
-	protected onTextFilesDirty(e: TextFileModelChangeEvent[]): void {
+	protected onTextFilesDirty(e: readonly TextFileModelChangeEvent[]): void {
 		if ((this.textFileService.getAutoSaveMode() !== AutoSaveMode.AFTER_SHORT_DELAY) && !this.isDocumentedEdited) {
 			this.updateDocumentEdited(); // no indication needed when auto save is enabled for short delay
 		}
@@ -46,7 +46,7 @@ export class NativeDirtyFilesTracker extends DirtyFilesTracker {
 		super.onTextFilesDirty(e);
 	}
 
-	protected onTextFilesSaved(e: TextFileModelChangeEvent[]): void {
+	protected onTextFilesSaved(e: readonly TextFileModelChangeEvent[]): void {
 		if (this.isDocumentedEdited) {
 			this.updateDocumentEdited();
 		}
@@ -54,7 +54,7 @@ export class NativeDirtyFilesTracker extends DirtyFilesTracker {
 		super.onTextFilesSaved(e);
 	}
 
-	protected onTextFilesSaveError(e: TextFileModelChangeEvent[]): void {
+	protected onTextFilesSaveError(e: readonly TextFileModelChangeEvent[]): void {
 		if (!this.isDocumentedEdited) {
 			this.updateDocumentEdited();
 		}
@@ -62,7 +62,7 @@ export class NativeDirtyFilesTracker extends DirtyFilesTracker {
 		super.onTextFilesSaveError(e);
 	}
 
-	protected onTextFilesReverted(e: TextFileModelChangeEvent[]): void {
+	protected onTextFilesReverted(e: readonly TextFileModelChangeEvent[]): void {
 		if (this.isDocumentedEdited) {
 			this.updateDocumentEdited();
 		}
diff --git a/src/vs/workbench/services/textfile/common/textFileEditorModelManager.ts b/src/vs/workbench/services/textfile/common/textFileEditorModelManager.ts
index 4de574861a01679f7461cdc05c2c29ebc96cb8d2..7a87bbb0bd636006cb7df23c0e3d25cde9214fa3 100644
--- a/src/vs/workbench/services/textfile/common/textFileEditorModelManager.ts
+++ b/src/vs/workbench/services/textfile/common/textFileEditorModelManager.ts
@@ -38,8 +38,8 @@ export class TextFileEditorModelManager extends Disposable implements ITextFileE
 	private readonly _onModelOrphanedChanged: Emitter<TextFileModelChangeEvent> = this._register(new Emitter<TextFileModelChangeEvent>());
 	readonly onModelOrphanedChanged: Event<TextFileModelChangeEvent> = this._onModelOrphanedChanged.event;
 
-	private _onModelsDirty!: Event<TextFileModelChangeEvent[]>;
-	get onModelsDirty(): Event<TextFileModelChangeEvent[]> {
+	private _onModelsDirty!: Event<readonly TextFileModelChangeEvent[]>;
+	get onModelsDirty(): Event<readonly TextFileModelChangeEvent[]> {
 		if (!this._onModelsDirty) {
 			this._onModelsDirty = this.debounce(this.onModelDirty);
 		}
@@ -47,8 +47,8 @@ export class TextFileEditorModelManager extends Disposable implements ITextFileE
 		return this._onModelsDirty;
 	}
 
-	private _onModelsSaveError!: Event<TextFileModelChangeEvent[]>;
-	get onModelsSaveError(): Event<TextFileModelChangeEvent[]> {
+	private _onModelsSaveError!: Event<readonly TextFileModelChangeEvent[]>;
+	get onModelsSaveError(): Event<readonly TextFileModelChangeEvent[]> {
 		if (!this._onModelsSaveError) {
 			this._onModelsSaveError = this.debounce(this.onModelSaveError);
 		}
@@ -56,8 +56,8 @@ export class TextFileEditorModelManager extends Disposable implements ITextFileE
 		return this._onModelsSaveError;
 	}
 
-	private _onModelsSaved!: Event<TextFileModelChangeEvent[]>;
-	get onModelsSaved(): Event<TextFileModelChangeEvent[]> {
+	private _onModelsSaved!: Event<readonly TextFileModelChangeEvent[]>;
+	get onModelsSaved(): Event<readonly TextFileModelChangeEvent[]> {
 		if (!this._onModelsSaved) {
 			this._onModelsSaved = this.debounce(this.onModelSaved);
 		}
@@ -65,8 +65,8 @@ export class TextFileEditorModelManager extends Disposable implements ITextFileE
 		return this._onModelsSaved;
 	}
 
-	private _onModelsReverted!: Event<TextFileModelChangeEvent[]>;
-	get onModelsReverted(): Event<TextFileModelChangeEvent[]> {
+	private _onModelsReverted!: Event<readonly TextFileModelChangeEvent[]>;
+	get onModelsReverted(): Event<readonly TextFileModelChangeEvent[]> {
 		if (!this._onModelsReverted) {
 			this._onModelsReverted = this.debounce(this.onModelReverted);
 		}
@@ -95,7 +95,7 @@ export class TextFileEditorModelManager extends Disposable implements ITextFileE
 		this.lifecycleService.onShutdown(this.dispose, this);
 	}
 
-	private debounce(event: Event<TextFileModelChangeEvent>): Event<TextFileModelChangeEvent[]> {
+	private debounce(event: Event<TextFileModelChangeEvent>): Event<readonly TextFileModelChangeEvent[]> {
 		return Event.debounce(event, (prev: TextFileModelChangeEvent[], cur: TextFileModelChangeEvent) => {
 			if (!prev) {
 				prev = [cur];
diff --git a/src/vs/workbench/services/textfile/common/textfiles.ts b/src/vs/workbench/services/textfile/common/textfiles.ts
index 43063dc200f6e4b478318c4aef38c27f84a866ff..568ad75afca1dedd26728018771efc08e60b36af 100644
--- a/src/vs/workbench/services/textfile/common/textfiles.ts
+++ b/src/vs/workbench/services/textfile/common/textfiles.ts
@@ -412,10 +412,10 @@ export interface ITextFileEditorModelManager {
 	readonly onModelReverted: Event<TextFileModelChangeEvent>;
 	readonly onModelOrphanedChanged: Event<TextFileModelChangeEvent>;
 
-	readonly onModelsDirty: Event<TextFileModelChangeEvent[]>;
-	readonly onModelsSaveError: Event<TextFileModelChangeEvent[]>;
-	readonly onModelsSaved: Event<TextFileModelChangeEvent[]>;
-	readonly onModelsReverted: Event<TextFileModelChangeEvent[]>;
+	readonly onModelsDirty: Event<readonly TextFileModelChangeEvent[]>;
+	readonly onModelsSaveError: Event<readonly TextFileModelChangeEvent[]>;
+	readonly onModelsSaved: Event<readonly TextFileModelChangeEvent[]>;
+	readonly onModelsReverted: Event<readonly TextFileModelChangeEvent[]>;
 
 	get(resource: URI): ITextFileEditorModel | undefined;