diff --git a/core/lib/Thelia/Module/DeliveryModuleInterface.php b/core/lib/Thelia/Module/DeliveryModuleInterface.php
index 2ef593ee5..b8ffcfc01 100644
--- a/core/lib/Thelia/Module/DeliveryModuleInterface.php
+++ b/core/lib/Thelia/Module/DeliveryModuleInterface.php
@@ -32,5 +32,5 @@ interface DeliveryModuleInterface extends BaseModuleInterface {
      *
      * @return mixed
      */
-    public function calculate();
+    public function calculate($country = null);
 }
\ No newline at end of file