diff --git a/utils/monitoring.js b/utils/monitoring.js
index c7ec7be6..ce934e27 100644
--- a/utils/monitoring.js
+++ b/utils/monitoring.js
@@ -59,7 +59,7 @@ const metricsCount = (promClient.register.getSingleMetric('count_items_metricsCo
 function _writeResponse(res, error) {
     let statusCode = 200;
     if (error) {
-        if (Number.isInteger(error.code)) {
+        if (error instanceof errors.ArsenalError && Number.isInteger(error.code)) {
             statusCode = error.code;
         } else {
             statusCode = 500;