diff --git a/extensions/typescript-language-features/src/features/fileConfigurationManager.ts b/extensions/typescript-language-features/src/features/fileConfigurationManager.ts
index 0cb8c3da539..9bdc174b858 100644
--- a/extensions/typescript-language-features/src/features/fileConfigurationManager.ts
+++ b/extensions/typescript-language-features/src/features/fileConfigurationManager.ts
@@ -7,8 +7,8 @@ import { workspace as Workspace, FormattingOptions, TextDocument, CancellationTo
 
 import * as Proto from '../protocol';
 import { ITypeScriptServiceClient } from '../typescriptService';
-import * as languageIds from '../utils/languageModeIds';
 import API from '../utils/api';
+import { isTypeScriptDocument } from '../utils/languageModeIds';
 
 function objsAreEqual<T>(a: T, b: T): boolean {
 	let keys = Object.keys(a);
@@ -175,8 +175,4 @@ function getImportModuleSpecifierPreference(config: WorkspaceConfiguration) {
 		case 'non-relative': return 'non-relative';
 		default: return undefined;
 	}
-}
-
-function isTypeScriptDocument(document: TextDocument) {
-	return document.languageId === languageIds.typescript || document.languageId === languageIds.typescriptreact;
-}
+}
\ No newline at end of file
diff --git a/extensions/typescript-language-features/src/utils/languageModeIds.ts b/extensions/typescript-language-features/src/utils/languageModeIds.ts
index 5fe187e13db..9be48067eda 100644
--- a/extensions/typescript-language-features/src/utils/languageModeIds.ts
+++ b/extensions/typescript-language-features/src/utils/languageModeIds.ts
@@ -14,4 +14,8 @@ export const jsxTags = 'jsx-tags';
 
 export function isSupportedLanguageMode(doc: vscode.TextDocument) {
 	return vscode.languages.match([typescript, typescriptreact, javascript, javascriptreact], doc) > 0;
+}
+
+export function isTypeScriptDocument(doc: vscode.TextDocument) {
+	return vscode.languages.match([typescript, typescriptreact], doc) > 0;
 }
\ No newline at end of file