diff -rupN commerce_old/modules/product_pricing/commerce_product_pricing.module commerce/modules/product_pricing/commerce_product_pricing.module
--- commerce_old/modules/product_pricing/commerce_product_pricing.module	2015-08-03 13:27:06.215682203 +0300
+++ commerce/modules/product_pricing/commerce_product_pricing.module	2015-08-03 13:28:00.573667810 +0300
@@ -86,11 +86,13 @@ function commerce_product_pricing_commer
           // Save the original value for use in subsequent calculations.
           $original = isset($items[$product_id][0]) ? $items[$product_id][0] : NULL;
         }
-
-        // Replace the data being displayed with data from a calculated price.
-        $items[$product_id] = array();
-        $items[$product_id][0] = commerce_product_calculate_sell_price($product);
-        $items[$product_id][0]['original'] = $original;
+        
+        if($original) {
+          // Replace the data being displayed with data from a calculated price.
+          $items[$product_id] = array();
+          $items[$product_id][0] = commerce_product_calculate_sell_price($product);
+          $items[$product_id][0]['original'] = $original;
+        }
       }
     }
   }