diff --git a/backend/src/common/envs.js b/backend/src/common/envs.js
index f1ae30de..5f131966 100644
--- a/backend/src/common/envs.js
+++ b/backend/src/common/envs.js
@@ -1,3 +1,5 @@
+// @ts-check
+
 const whitelist = process.env.WHITELIST
   ? process.env.WHITELIST.split(",")
   : undefined;