diff --git a/addons/web/static/src/js/view_form.js b/addons/web/static/src/js/view_form.js
index 1af8f5ed792..69850139158 100644
--- a/addons/web/static/src/js/view_form.js
+++ b/addons/web/static/src/js/view_form.js
@@ -2664,7 +2664,7 @@ openerp.web.form.FieldMany2Many = openerp.web.form.Field.extend({
         return [commands.replace_with(this.dataset.ids)];
     },
     validate: function() {
-        this.invalid = this.required && !this.dataset.ids.length ? true : false ;
+        this.invalid = this.required && _(this.dataset.ids).isEmpty();
     },
     is_readonly: function() {
         return this.readonly || this.force_readonly;