diff --git a/couriers/lib/abstract_courier.js b/couriers/lib/abstract_courier.js
index 305a3d1..7f7fa2c 100644
--- a/couriers/lib/abstract_courier.js
+++ b/couriers/lib/abstract_courier.js
@@ -36,7 +36,7 @@
 			throw new Error('config.number_of_token_per_job is undefined.');
 		}
 
-		this.config = _.merge(default_config, this.config);
+		this.config = _.merge(this.config, default_config);
 	}
 
 	/**
@@ -310,4 +310,4 @@
 
 	module.exports = AbstractCourier;
 
-})();
\ No newline at end of file
+})();