diff --git a/addons/web/static/src/js/views/calendar/calendar_quick_create.js b/addons/web/static/src/js/views/calendar/calendar_quick_create.js
index 8329ca83bd810..e89881d0e933b 100644
--- a/addons/web/static/src/js/views/calendar/calendar_quick_create.js
+++ b/addons/web/static/src/js/views/calendar/calendar_quick_create.js
@@ -77,6 +77,11 @@ var QuickCreate = Dialog.extend({
     _quickAdd: function (dataCalendar) {
         dataCalendar = $.extend({}, this.dataTemplate, dataCalendar);
         var val = this.$('input').val().trim();
+        if (!val) {
+            this.$('label, input').addClass('o_field_invalid');
+            var warnings = _.str.sprintf('<ul><li>%s</li></ul>', _t("Summary"));
+            this.do_warn(_t("The following field is invalid:"), warnings);
+        }
         dataCalendar.title = val;
         return (val)? this.trigger_up('quickCreate', {data: dataCalendar, options: this.options}) : false;
     },
diff --git a/addons/web/static/src/xml/web_calendar.xml b/addons/web/static/src/xml/web_calendar.xml
index e0cb81c6e9b80..9a64c7258d888 100644
--- a/addons/web/static/src/xml/web_calendar.xml
+++ b/addons/web/static/src/xml/web_calendar.xml
@@ -95,8 +95,8 @@
 
     <main t-name="CalendarView.quick_create" class="o_calendar_quick_create">
         <div class="form-group">
-            <label for='name' class='col-form-label'>Summary:</label>
-            <input type='text' name='name' class="o_input" t-att-value="widget.dataTemplate.name or None"/>
+            <label for='name' class='col-form-label o_form_label'>Summary:</label>
+            <input type='text' name='name' class="o_input o_required_modifier" t-att-value="widget.dataTemplate.name or None"/>
         </div>
     </main>
 </template>