diff --git a/addons/web/static/src/js/widgets/attach_document.js b/addons/web/static/src/js/widgets/attach_document.js
index 3175875c151..a4a72a62765 100644
--- a/addons/web/static/src/js/widgets/attach_document.js
+++ b/addons/web/static/src/js/widgets/attach_document.js
@@ -109,10 +109,10 @@ var AttachDocument = Widget.extend({
      */
     _onFileLoaded: function () {
         var self = this;
+        // the first argument isn't a file but the jQuery.Event
+        var files = Array.prototype.slice.call(arguments, 1);
         return new Promise(function (resolve) {
             if (self.node.attrs.action) {
-                // the first argument isn't a file but the jQuery.Event
-                var files = Array.prototype.slice.call(arguments, 1);
                 self._rpc({
                     model: self.res_model,
                     method: self.node.attrs.action,
diff --git a/addons/web/static/tests/views/form_tests.js b/addons/web/static/tests/views/form_tests.js
index c01a1c46fb3..f41dbcb7f28 100644
--- a/addons/web/static/tests/views/form_tests.js
+++ b/addons/web/static/tests/views/form_tests.js
@@ -6801,6 +6801,32 @@ QUnit.module('Views', {
         delete widgetRegistry.map.test;
     });
 
+    QUnit.test('attach document widget calls action with attachment ids', async function (assert) {
+        assert.expect(1);
+
+        var form = await createView({
+            View: FormView,
+            model: 'partner',
+            data: this.data,
+            mockRPC: function (route, args) {
+                if (args.method === 'my_action') {
+                    assert.deepEqual(args.kwargs.attachment_ids, [5, 2]);
+                    return Promise.resolve();
+                }
+                return this._super.apply(this, arguments);
+            },
+            arch: '<form>' +
+                    '<widget name="attach_document" action="my_action"/>' +
+                '</form>',
+        });
+
+        var onFileLoadedEventName = form.$('.o_form_binary_form').attr('target')
+        // trigger _onFileLoaded function
+        $(window).trigger(onFileLoadedEventName, [{id: 5}, {id:2}]);
+
+        form.destroy();
+    });
+
     QUnit.test('support header button as widgets on form statusbar', async function (assert) {
         assert.expect(2);