diff --git a/src/main.rs b/src/main.rs
index 2eace02..88c7ed8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -8,6 +8,7 @@ use chrono::Local;
 use std::cell::Cell;
 use std::rc::Rc;
 
+use gtk::gio::{Notification, NotificationPriority};
 use gtk::glib;
 use gtk::glib::clone;
 use gtk::prelude::*;
@@ -19,9 +20,9 @@ const DUR_MIN: f64 = 1.0;
 const INTERVAL_SEC: u32 = 1;
 
 fn main() -> glib::ExitCode {
-    let application = gtk::Application::builder().application_id(APP_ID).build();
-    application.connect_activate(build_ui);
-    application.run()
+    let app = gtk::Application::builder().application_id(APP_ID).build();
+    app.connect_activate(move |app| build_ui(app));
+    app.run()
 }
 
 fn build_ui(app: &gtk::Application) {
@@ -74,22 +75,27 @@ fn build_ui(app: &gtk::Application) {
     window.set_child(Some(&container));
     window.present();
 
-    // we are using a closure to capture the label (else we could also use a normal function)
-    let tick = move || {
+    let tick = clone!(@strong app => move || {
         if running.get() {
             progress += ((INTERVAL_SEC as f64) / 60.0) / DUR_MIN;
             progress_bar.set_fraction(progress);
         }
 
         if progress > 1.0 {
-            // todo
+            eprintln!("Time over.");
+
+            // TODO: Notification does not show up
+            let notification = Notification::new("Alert");
+            notification.set_body(Some("Time is over"));
+            notification.set_priority(NotificationPriority::Urgent);
+            app.send_notification(Some(APP_ID), &notification);
         }
 
         let time = current_time();
         label.set_text(&time);
         // we could return glib::ControlFlow::Break to stop our clock after this tick
         glib::ControlFlow::Continue
-    };
+    });
 
     // executes the closure once every `INTERVAL_SEC` seconds
     glib::timeout_add_seconds_local(INTERVAL_SEC, tick);