diff --git a/sao/src/model.js b/sao/src/model.js
index bd10d454e2..c8e7546fd2 100644
--- a/sao/src/model.js
+++ b/sao/src/model.js
@@ -2390,7 +2390,7 @@
                         if (record2) {
                             var vals_to_set = {};
                             for (var key in vals) {
-                                if (!(key in new_field_names)) {
+                                if (!Object.prototype.hasOwnProperty.call(new_field_names, key)) {
                                     vals_to_set[key] = vals[key];
                                 }
                             }