diff --git a/app/controllers/vouchers_controller.rb b/app/controllers/vouchers_controller.rb
index 0dc56aa..1474407 100644
--- a/app/controllers/vouchers_controller.rb
+++ b/app/controllers/vouchers_controller.rb
@@ -31,7 +31,7 @@ class VouchersController < ApplicationController
       end
     else
 
-      render json: "Voucher is not valid. Whitelisted: " + params[:voucher].in?(whitelist).to_s + ". Exists: " + Voucher.exists?(vouchee: params[:voucher]).to_s + ". " + whitelist, status: :unprocessable_entity
+      render json: "Voucher is not valid. Whitelisted: " + params[:voucher].in?(whitelist).to_s + ". Exists: " + Voucher.exists?(vouchee: params[:voucher]).to_s + ". " + whitelist.to_s, status: :unprocessable_entity
     end