diff --git a/src/dndbuster/app.py b/src/dndbuster/app.py
index 17f569f..5ea9eb1 100644
--- a/src/dndbuster/app.py
+++ b/src/dndbuster/app.py
@@ -25,7 +25,7 @@ class Application(Adw.Application):
         self.window = AppWindow(application=self)
         self.window.present()
 
-    def notify_timer(self) -> None:
+    def send_notification_timeout(self) -> None:
         notification = Gio.Notification()
         notification.set_title('Timeout')
         notification.set_body('The time is over and your do-not-disturb mode just got busted!')
@@ -59,7 +59,7 @@ class AppWindow(Gtk.ApplicationWindow):
         self.progress_bar = Gtk.ProgressBar(visible=False)
         self.box.append(self.progress_bar)
 
-        self.timer = None
+        self.timer = Timer()
 
     def update_progress(self) -> bool:
         total_min = 25
@@ -69,7 +69,7 @@ class AppWindow(Gtk.ApplicationWindow):
         self.progress_bar.set_fraction(progress)
 
         if progress >= 1:
-            self.app.notify_timer()
+            self.app.send_notification_timeout()
             # Stop regularly calling update_progress()
             return False
 
@@ -77,18 +77,18 @@ class AppWindow(Gtk.ApplicationWindow):
         return not self.timer.is_paused()
 
     def on_button_start_restart_clicked(self, _widget) -> None:
-        if self.timer is None:
-            self.add_timer()
+        if not self.timer.is_started():
+            self.reset_start_timer()
 
             self.button_start_restart.set_label("Restart")
             self.button_pause_resume.set_visible(True)
         else:
-            self.add_timer()
+            self.reset_start_timer()
 
             self.update_label()
 
-    def add_timer(self) -> None:
-        self.timer = Timer()
+    def reset_start_timer(self) -> None:
+        self.timer.reset()
         self.timer.start()
         self.progress_bar.set_visible(True)
         self.add_timeout()