diff --git a/app/controllers/vouchers_controller.rb b/app/controllers/vouchers_controller.rb
index cfec1a3..835ce79 100644
--- a/app/controllers/vouchers_controller.rb
+++ b/app/controllers/vouchers_controller.rb
@@ -5,7 +5,7 @@ class VouchersController < ApplicationController
   # GET /vouchers
   def index
     @vouchers = Voucher.all
-    whitelist = %x{mc-whitelist-users}.gsub("\n", "")
+    whitelist = `mc-whitelist-users`.gsub("\n", "")
 
     render json: { :vouchers => @vouchers, :whitelist => whitelist }.to_json
   end
@@ -19,7 +19,7 @@ class VouchersController < ApplicationController
   def create
     # Logic for creating a voucher
     output = ""
-    whitelist = %x(mc-whitelist-users).gsub("\n", "").split(", ")
+    whitelist = `mc-whitelist-users`.gsub("\n", "").split(", ")
 
     if Voucher.exists?(vouchee: params[:voucher]) && params[:voucher].in?(whitelist)
       @voucher = Voucher.new(voucher_params)