diff --git a/retailcrm/include/api/class-wc-retailcrm-client-v5.php b/retailcrm/include/api/class-wc-retailcrm-client-v5.php
index cbc6de9..f51984f 100644
--- a/retailcrm/include/api/class-wc-retailcrm-client-v5.php
+++ b/retailcrm/include/api/class-wc-retailcrm-client-v5.php
@@ -245,7 +245,7 @@
 
             return $this->client->makeRequest(
                 "/custom-fields/$entity/edit/{$customField['code']}",
-                $this->client::METHOD_POST,
+                WC_Retailcrm_Request::METHOD_POST,
                 array('customField' => json_encode($customField))
             );
         }