diff --git a/webapp/services/callback/MarketCallbackBase.php b/webapp/services/callback/MarketCallbackBase.php
index b11702ee..423d9035 100644
--- a/webapp/services/callback/MarketCallbackBase.php
+++ b/webapp/services/callback/MarketCallbackBase.php
@@ -2,6 +2,7 @@
 
 namespace services;
 
+require_once('phpcommon/bignumber.php');
 use phpcommon\SqlHelper;
 use phpcommon;