diff --git a/packages/backend-common/config.d.ts b/packages/backend-common/config.d.ts
index 53e0e0b838..ceb9706ca9 100644
--- a/packages/backend-common/config.d.ts
+++ b/packages/backend-common/config.d.ts
@@ -27,7 +27,7 @@ export interface Config {
        * Format is base64 24-bit key
        * @visibility secret
        */
-      secret?: string;
+      secret: string;
     };
 
     baseUrl: string; // defined in core, but repeated here without doc