diff --git a/commerce_coupon_ui.module b/commerce_coupon_ui.module
index 6565730073179867cfe22e467f50355d93bf5fe1..9a3dee75708210aefdbeee33204dd71026d5a802 100644
--- a/commerce_coupon_ui.module
+++ b/commerce_coupon_ui.module
@@ -40,9 +40,8 @@ function commerce_coupon_ui_menu() {
       $items['admin/commerce/coupons/add/' . strtr($type, array('_' => '-'))] = array(
         'title' => 'Create !name',
         'title arguments' => array('!name' => $coupon_type->label),
-        'page callback' => 'drupal_get_form',
         'page callback' => 'commerce_coupon_ui_coupon_form_wrapper',
-        'page arguments' => array(commerce_coupon_create($type)),
+        'page arguments' => array(commerce_coupon_create($type), 'add'),
         'access callback' => 'commerce_coupon_access',
         'access arguments' => array('create', $type),
       );
@@ -53,7 +52,7 @@ function commerce_coupon_ui_menu() {
   $items['admin/commerce/coupons/%commerce_coupon'] = array(
     'title' => 'Edit',
     'page callback' => 'commerce_coupon_ui_coupon_form_wrapper',
-    'page arguments' => array(3),
+    'page arguments' => array(3, 'edit'),
     'access callback' => 'entity_access',
     'access arguments' => array('update', 'commerce_coupon', 3),
     'weight' => 0,
@@ -247,14 +246,14 @@ function theme_commerce_coupon_ui_add_list($variables) {
  * @param $coupon
  *   The coupon object being edited by this form.
  */
-function commerce_coupon_ui_coupon_form_wrapper($coupon) {
+function commerce_coupon_ui_coupon_form_wrapper($coupon, $op = NULL) {
   // Add the breadcrumb for the form's location.
   commerce_coupon_ui_set_breadcrumb();
 
   // Include the forms file from the Coupon module.
   module_load_include('inc', 'commerce_coupon', 'includes/commerce_coupon_ui.forms');
 
-  return drupal_get_form('commerce_coupon_form', $coupon);
+  return drupal_get_form('commerce_coupon_form', $coupon, $op);
 }
 
 /**
diff --git a/includes/commerce_coupon_ui.forms.inc b/includes/commerce_coupon_ui.forms.inc
index 4a5bd90be165fe587fdc917ef0957b21369631b1..1ffb8555acaba2b3f8ce57ce6017c0f36527aeac 100644
--- a/includes/commerce_coupon_ui.forms.inc
+++ b/includes/commerce_coupon_ui.forms.inc
@@ -52,12 +52,16 @@ function commerce_coupon_form_validate(&$form, &$form_state) {
     form_set_error('is_active', t('You can\'t enable a coupon of a coupon type that is disabled'));
   }
 
-  if ($form_state['op'] == 'add') {
+  if ($form_state['op'] == 'add' || $form_state['op'] == 'edit') {
     $lang_code = field_language('commerce_coupon', $form_state['commerce_coupon'], 'commerce_coupon_code');
     if (isset($form_state['values']['commerce_coupon_code'][$lang_code][0]['value'])) {
       $coupon_code = $form_state['values']['commerce_coupon_code'][$lang_code][0]['value'];
       if (!empty($coupon_code) && commerce_coupon_code_exists($coupon_code)) {
-        form_set_error('commerce_coupon_code][' . $lang_code, t('This coupon code is already in use.'));
+        // Don't invalidate duplicate code if we are simply updating one.
+        if ($form_state['op'] == 'add' || (isset($coupon->commerce_coupon_code) &&
+          $coupon->commerce_coupon_code[$lang_code][0]['value'] != $coupon_code)) {
+          form_set_error('commerce_coupon_code][' . $lang_code, t('This coupon code is already in use.'));
+        }
       }
     }
   }