diff --git a/extensions/typescript/package.json b/extensions/typescript/package.json
index b76a143d7b4..a2b966da2b8 100644
--- a/extensions/typescript/package.json
+++ b/extensions/typescript/package.json
@@ -417,6 +417,19 @@
             "string",
             "null"
           ],
+          "enum": [
+            "de",
+            "es",
+            "en",
+            "fr",
+            "it",
+            "ja",
+            "ko",
+            "ru",
+            "zh-CN",
+            "zh-TW",
+            null
+          ],
           "default": null,
           "description": "%typescript.locale%",
           "scope": "window"
@@ -598,4 +611,4 @@
       }
     ]
   }
-}
+}
\ No newline at end of file