diff --git a/includes/commerce_coupon.controller.inc b/includes/commerce_coupon.controller.inc
index cbe2dbc..f511b75 100644
--- a/includes/commerce_coupon.controller.inc
+++ b/includes/commerce_coupon.controller.inc
@@ -76,7 +76,7 @@ class CommerceCouponEntityController extends DrupalCommerceEntityController {
    */
   public function attachLoad(&$queried_coupons, $revision_id = FALSE) {
     foreach ($queried_coupons as $coupon_id => &$commerce_coupon) {
-      $commerce_coupon->data = unserialize($commerce_coupon->data);
+      $commerce_coupon->data = unserialize((string) $commerce_coupon->data);
     }
 
     // Call the default attachLoad().