diff --git a/extensions/typescript-language-features/src/languageFeatures/callHierarchy.ts b/extensions/typescript-language-features/src/languageFeatures/callHierarchy.ts
index a90e68fd27c..ebebf6e6464 100644
--- a/extensions/typescript-language-features/src/languageFeatures/callHierarchy.ts
+++ b/extensions/typescript-language-features/src/languageFeatures/callHierarchy.ts
@@ -14,12 +14,6 @@ import { DocumentSelector } from '../utils/documentSelector';
 import { parseKindModifier } from '../utils/modifiers';
 import * as typeConverters from '../utils/typeConverters';
 
-namespace Experimental {
-	export interface CallHierarchyItem extends Proto.CallHierarchyItem {
-		readonly kindModifiers?: string;
-	}
-}
-
 class TypeScriptCallHierarchySupport implements vscode.CallHierarchyProvider {
 	public static readonly minVersion = API.v380;
 
@@ -83,7 +77,7 @@ function isSourceFileItem(item: Proto.CallHierarchyItem) {
 	return item.kind === PConst.Kind.script || item.kind === PConst.Kind.module && item.selectionSpan.start.line === 1 && item.selectionSpan.start.offset === 1;
 }
 
-function fromProtocolCallHierarchyItem(item: Experimental.CallHierarchyItem): vscode.CallHierarchyItem {
+function fromProtocolCallHierarchyItem(item: Proto.CallHierarchyItem): vscode.CallHierarchyItem {
 	const useFileName = isSourceFileItem(item);
 	const name = useFileName ? path.basename(item.file) : item.name;
 	const detail = useFileName ? vscode.workspace.asRelativePath(path.dirname(item.file)) : '';