diff --git a/extensions/typescript-language-features/src/tsServer/spawner.ts b/extensions/typescript-language-features/src/tsServer/spawner.ts
index 092ad4f0fb6..51a4096f9b3 100644
--- a/extensions/typescript-language-features/src/tsServer/spawner.ts
+++ b/extensions/typescript-language-features/src/tsServer/spawner.ts
@@ -164,11 +164,9 @@ export class TypeScriptServerSpawner {
 		let tsServerLogFile: string | undefined;
 
 		if (kind === TsServerProcessKind.Syntax) {
-			if (semver.gte(API.v400rc.fullVersionString, apiVersion.fullVersionString)) {
-				args.push('--serverMode');
-				args.push('partialSemantic');
-			}
-			else {
+			if (semver.gte(API.v401rc.fullVersionString, apiVersion.fullVersionString)) {
+				args.push('--serverMode', 'partialSemantic');
+			} else {
 				args.push('--syntaxOnly');
 			}
 		}
diff --git a/extensions/typescript-language-features/src/utils/api.ts b/extensions/typescript-language-features/src/utils/api.ts
index f797e578121..ea9c2493e8a 100644
--- a/extensions/typescript-language-features/src/utils/api.ts
+++ b/extensions/typescript-language-features/src/utils/api.ts
@@ -34,7 +34,7 @@ export default class API {
 	public static readonly v380 = API.fromSimpleString('3.8.0');
 	public static readonly v381 = API.fromSimpleString('3.8.1');
 	public static readonly v390 = API.fromSimpleString('3.9.0');
-	public static readonly v400rc = API.fromSimpleString('4.0.0-rc');
+	public static readonly v401rc = API.fromSimpleString('4.0.1-rc');
 	public static readonly v400 = API.fromSimpleString('4.0.0');
 
 	public static fromVersionString(versionString: string): API {