diff --git a/src/vs/base/browser/ui/breadcrumbs/breadcrumbsWidget.ts b/src/vs/base/browser/ui/breadcrumbs/breadcrumbsWidget.ts
index d4b8c1ddc45..9910bf95f55 100644
--- a/src/vs/base/browser/ui/breadcrumbs/breadcrumbsWidget.ts
+++ b/src/vs/base/browser/ui/breadcrumbs/breadcrumbsWidget.ts
@@ -274,7 +274,7 @@ export class BreadcrumbsWidget {
 		this._onDidSelectItem.fire({ type: 'select', item: this._items[this._selectedItemIdx], node: this._nodes[this._selectedItemIdx], payload });
 	}
 
-	getItems(): ReadonlyArray<BreadcrumbsItem> {
+	getItems(): readonly BreadcrumbsItem[] {
 		return this._items;
 	}
 
diff --git a/src/vs/editor/contrib/codeAction/codeAction.ts b/src/vs/editor/contrib/codeAction/codeAction.ts
index 19ef4bfc435..57fab087807 100644
--- a/src/vs/editor/contrib/codeAction/codeAction.ts
+++ b/src/vs/editor/contrib/codeAction/codeAction.ts
@@ -32,7 +32,7 @@ export class CodeActionSet {
 		}
 	}
 
-	public readonly actions: ReadonlyArray<CodeAction>;
+	public readonly actions: readonly CodeAction[];
 
 	public constructor(actions: CodeAction[]) {
 		this.actions = mergeSort(actions, CodeActionSet.codeActionsComparator);
diff --git a/src/vs/workbench/api/browser/mainThreadSaveParticipant.ts b/src/vs/workbench/api/browser/mainThreadSaveParticipant.ts
index 9a629ea8eed..ce105f8ece6 100644
--- a/src/vs/workbench/api/browser/mainThreadSaveParticipant.ts
+++ b/src/vs/workbench/api/browser/mainThreadSaveParticipant.ts
@@ -306,7 +306,7 @@ class CodeActionOnSaveParticipant implements ISaveParticipant {
 		}
 	}
 
-	private async applyCodeActions(actionsToRun: ReadonlyArray<CodeAction>) {
+	private async applyCodeActions(actionsToRun: readonly CodeAction[]) {
 		for (const action of actionsToRun) {
 			await applyCodeAction(action, this._bulkEditService, this._commandService);
 		}
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index 7e440c3e0a6..8a8cf6bd045 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -315,8 +315,8 @@ export interface ISerializedDocumentFilter {
 }
 
 export interface ISerializedSignatureHelpProviderMetadata {
-	readonly triggerCharacters: ReadonlyArray<string>;
-	readonly retriggerCharacters: ReadonlyArray<string>;
+	readonly triggerCharacters: readonly string[];
+	readonly retriggerCharacters: readonly string[];
 }
 
 export interface MainThreadLanguageFeaturesShape extends IDisposable {