diff --git a/src/model.js b/src/model.js
index 7cf913f4aa..2e70ad2ce1 100644
--- a/src/model.js
+++ b/src/model.js
@@ -2268,7 +2268,7 @@
             return this.set(record, value, true);
         },
         set_on_change: function(record, value) {
-            var fields;
+            var fields, new_fields;
             record._changed[this.name] = true;
             this._set_default_value(record);
             if (value instanceof Array) {