diff --git a/extensions/typescript/src/typescriptMain.ts b/extensions/typescript/src/typescriptMain.ts
index 9c20725093204c054df8042368254a724be454c5..3938f9888f2ffa8ad37996fbc50b96fcca595268 100644
--- a/extensions/typescript/src/typescriptMain.ts
+++ b/extensions/typescript/src/typescriptMain.ts
@@ -613,7 +613,7 @@ class TypeScriptServiceClientHost implements ITypescriptServiceClientHost {
 	}
 
 	private findLanguage(file: string): Thenable<LanguageProvider | null> {
-		return workspace.openTextDocument(file).then((doc: TextDocument) => {
+		return workspace.openTextDocument(this.client.asUrl(file)).then((doc: TextDocument) => {
 			for (const language of this.languages) {
 				if (language.handles(file, doc)) {
 					return language;