diff --git a/commerce_discount.rules.inc b/commerce_discount.rules.inc
index 719344e..e0e658e 100644
--- a/commerce_discount.rules.inc
+++ b/commerce_discount.rules.inc
@@ -789,7 +789,7 @@ function commerce_discount_percentage(EntityDrupalWrapper $wrapper, $discount_na
   $discount_wrapper = entity_metadata_wrapper('commerce_discount', $discount_name);
   $rate = $discount_wrapper->commerce_discount_offer->commerce_percentage->value() / 100;
   // Get the line item types to apply the discount to.
-  $line_item_types = variable_get('commerce_discount_line_item_types', array('product' => 'product'));
+  $line_item_types = variable_get('commerce_discount_line_item_types', array_diff(commerce_product_line_item_types(), array('product_discount')));
 
   switch ($wrapper->type()) {
     case 'commerce_order':
@@ -809,7 +809,7 @@ function commerce_discount_percentage(EntityDrupalWrapper $wrapper, $discount_na
       $calculated_discount = 0;
       // Loop the line items of the order and calculate the total discount.
       foreach ($wrapper->commerce_line_items as $line_item_wrapper) {
-        if (!empty($line_item_types[$line_item_wrapper->type->value()])) {
+        if (in_array($line_item_wrapper->type->value(), $line_item_types)) {
           $line_item_total = commerce_price_wrapper_value($line_item_wrapper, 'commerce_total', TRUE);
           $calculated_discount += $line_item_total['amount'] * $rate;
         }
@@ -835,7 +835,7 @@ function commerce_discount_percentage(EntityDrupalWrapper $wrapper, $discount_na
     case 'commerce_line_item':
       // Check if the line item is configured in the settings to apply the
       // discount.
-      if (empty($line_item_types[$wrapper->getBundle()])) {
+      if (!in_array($wrapper->getBundle(), $line_item_types)) {
         return;
       }
 
diff --git a/includes/commerce_discount.admin.inc b/includes/commerce_discount.admin.inc
index bbc25d9..644b0b0 100644
--- a/includes/commerce_discount.admin.inc
+++ b/includes/commerce_discount.admin.inc
@@ -388,7 +388,7 @@ function commerce_discount_settings() {
   $form['commerce_discount_line_item_types'] = array(
     '#type' => 'checkboxes',
     '#title' => t('Line item types to use for discounts'),
-    '#default_value' => variable_get('commerce_discount_line_item_types', array('product')),
+    '#default_value' => variable_get('commerce_discount_line_item_types', array_diff(commerce_product_line_item_types(), array('product_discount'))),
     '#options' => $types,
     '#description' => t('Select the line item types that will be taken into account for calculating the discount amounts in percentage offers.'),
   );