diff --git a/modules/checkout/includes/commerce_checkout.pages.inc b/modules/checkout/includes/commerce_checkout.pages.inc
index 2104dbe..2486357 100644
--- a/modules/checkout/includes/commerce_checkout.pages.inc
+++ b/modules/checkout/includes/commerce_checkout.pages.inc
@@ -10,6 +10,10 @@
  * Redirects invalid checkout attempts or displays the checkout form if valid.
  */
 function commerce_checkout_router($order, $checkout_page = NULL) {
+
+  // Back button must reload page.
+  drupal_add_http_header('Cache-Control', 'no-cache, no-store, must-revalidate, post-check=0, pre-check=0');
+
   $checkout_pages = commerce_checkout_pages();
 
   // If no checkout page is specified, default to the first one.