diff --git a/src/hooks/useAuth.ts b/src/hooks/useAuth.ts
index fcbffcd..56b5d55 100644
--- a/src/hooks/useAuth.ts
+++ b/src/hooks/useAuth.ts
@@ -43,7 +43,8 @@ export function useAuth() {
           body: JSON.stringify({
             email,
             password,
-            ...(orgId ? { org_id: Number(orgId) } : {}),
+            // dev's user-service unmarshals org_id as a string.
+            ...(orgId ? { org_id: orgId } : {}),
           }),
         });