diff --git a/addons/web/static/src/js/fields/abstract_field.js b/addons/web/static/src/js/fields/abstract_field.js
index e25c02f781e..cef45c2a976 100644
--- a/addons/web/static/src/js/fields/abstract_field.js
+++ b/addons/web/static/src/js/fields/abstract_field.js
@@ -407,6 +407,7 @@ var AbstractField = Widget.extend({
             this._isValid = true;
         } catch (e) {
             this._isValid = false;
+            this.trigger_up('set_dirty', {dataPointID: this.dataPointID});
             return $.Deferred().reject();
         }
         if (!(options && options.forceChange) && this._isSameValue(value)) {
diff --git a/addons/web/static/src/js/views/basic/basic_controller.js b/addons/web/static/src/js/views/basic/basic_controller.js
index 481fc0cf4dd..c899530de07 100644
--- a/addons/web/static/src/js/views/basic/basic_controller.js
+++ b/addons/web/static/src/js/views/basic/basic_controller.js
@@ -19,6 +19,7 @@ var BasicController = AbstractController.extend(FieldManagerMixin, {
     custom_events: _.extend({}, AbstractController.prototype.custom_events, FieldManagerMixin.custom_events, {
         discard_changes: '_onDiscardChanges',
         reload: '_onReload',
+        set_dirty: '_onSetDirty',
         sidebar_data_asked: '_onSidebarDataAsked',
         translate: '_onTranslate',
     }),
@@ -553,6 +554,14 @@ var BasicController = AbstractController.extend(FieldManagerMixin, {
             });
         }
     },
+    /**
+     * @private
+     * @param {OdooEvent} ev
+     */
+    _onSetDirty: function (ev) {
+        ev.stopPropagation(); // prevent other controllers from handling this request
+        this.model.setDirty(ev.data.dataPointID);
+    },
     /**
      * Handler used to get all the data necessary when a custom action is
      * performed through the sidebar.
diff --git a/addons/web/static/src/js/views/basic/basic_model.js b/addons/web/static/src/js/views/basic/basic_model.js
index 9e7fb8b78ef..57c4a1f3743 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -947,6 +947,17 @@ var BasicModel = AbstractModel.extend({
         record.fields = _.defaults(record.fields, viewInfo.fields);
         record.fieldsInfo = _.defaults(record.fieldsInfo, viewInfo.fieldsInfo);
     },
+    /**
+     * Manually sets a resource as dirty. This is used to notify that a field
+     * has been modified, but with an invalid value. In that case, the value is
+     * not sent to the basic model, but the record should still be flagged as
+     * dirty so that it isn't discarded without any warning.
+     *
+     * @param {string} id a resource id
+     */
+    setDirty: function (id) {
+        this.localData[id]._isDirty = true;
+    },
     /**
      * For list resources, this changes the orderedBy key.
      *
diff --git a/addons/web/static/tests/fields/relational_fields_tests.js b/addons/web/static/tests/fields/relational_fields_tests.js
index 486fa22d56c..a96e21cc443 100644
--- a/addons/web/static/tests/fields/relational_fields_tests.js
+++ b/addons/web/static/tests/fields/relational_fields_tests.js
@@ -6168,6 +6168,42 @@ QUnit.module('relational_fields', {
         form.destroy();
     });
 
+    QUnit.test('one2many with default value: edit line to make it invalid', function (assert) {
+        assert.expect(3);
+
+        this.data.partner.fields.p.default = [
+            [0, false, {foo: "coucou", int_field: 5}],
+        ];
+
+        var form = createView({
+            View: FormView,
+            model: 'partner',
+            data: this.data,
+            arch:'<form string="Partners">' +
+                    '<field name="p">' +
+                        '<tree editable="bottom">' +
+                            '<field name="foo"/>' +
+                            '<field name="int_field"/>' +
+                        '</tree>' +
+                    '</field>' +
+                '</form>',
+        });
+
+        // edit the line and enter an invalid value for int_field
+        form.$('.o_data_row .o_data_cell:nth(1)').click();
+        form.$('.o_field_widget[name=int_field]').val('e').trigger('input');
+        form.$el.click(); // try to validate the line
+
+        assert.strictEqual(form.$('.o_data_row.o_selected_row').length, 1,
+            "line should not have been removed and should still be in edition");
+        assert.strictEqual($('.modal').length, 1,
+            "a confirmation dialog should be opened");
+        assert.ok(form.$('.o_field_widget[name=int_field]').hasClass('o_field_invalid'),
+            "should indicate that int_field is invalid");
+
+        form.destroy();
+    });
+
     QUnit.module('FieldMany2Many');
 
     QUnit.test('many2many kanban: edition', function (assert) {