diff --git a/src/briar/gtk/containers/chat.py b/src/briar/gtk/containers/chat.py
index 3ffd81e77b13003a6e1532d6158de9c7fc0da5a4..12b71035c42ddbcbc7e4c9f29ec94772ae6e6a3e 100644
--- a/src/briar/gtk/containers/chat.py
+++ b/src/briar/gtk/containers/chat.py
@@ -6,20 +6,22 @@ from gi.repository import GLib, Gtk
 
 from briar.api.models.private_chat import PrivateChat
 from briar.gtk.container import Container
-from briar.gtk.define import App
+from briar.gtk.define import APP
 
 
 class ChatContainer(Container):
 
+    CONTAINER_UI = "/app/briar/gtk/ui/chat.ui"
+
     def __init__(self, contact_id):
         super().__init__()
-        self._api = App().api
+        self._api = APP().api
         self._contact_id = contact_id
         self._setup_view()
         self._load_content()
 
     def _setup_view(self):
-        self.builder.add_from_resource("/app/briar/gtk/ui/chat.ui")
+        self.builder.add_from_resource(self.CONTAINER_UI)
         self.add(self.builder.get_object("chat"))
         self.builder.connect_signals(self)
         chat_entry = self.builder.get_object("chat_entry")
diff --git a/src/briar/gtk/containers/main.py b/src/briar/gtk/containers/main.py
index c3176164aac4c0897901a4a2a4db43249cbbfa49..2198fd007d682f789ac64f53ff95f2c61c182a36 100644
--- a/src/briar/gtk/containers/main.py
+++ b/src/briar/gtk/containers/main.py
@@ -6,19 +6,21 @@ from gi.repository import GLib, Gtk
 
 from briar.api.models.contacts import Contacts
 from briar.gtk.container import Container
-from briar.gtk.define import App
+from briar.gtk.define import APP
 
 
 class MainContainer(Container):
 
+    CONTAINER_UI = "/app/briar/gtk/ui/main.ui"
+
     def __init__(self):
         super().__init__()
-        self._api = App().api
+        self._api = APP().api
         self._setup_view()
         self._load_content()
 
     def _setup_view(self):
-        self.builder.add_from_resource("/app/briar/gtk/ui/main.ui")
+        self.builder.add_from_resource(self.CONTAINER_UI)
         self.add(self.builder.get_object("contacts_list"))
         self.builder.connect_signals(self)
 
@@ -36,4 +38,4 @@ class MainContainer(Container):
     # pylint: disable=unused-argument
     @staticmethod
     def _contact_clicked(widget, contact_id):
-        GLib.idle_add(App().window.open_private_chat, contact_id)
+        GLib.idle_add(APP().window.open_private_chat, contact_id)
diff --git a/src/briar/gtk/containers/startup.py b/src/briar/gtk/containers/startup.py
index c564164160d157e7bb6cec0ffd34ec8d1d4d0439..581f03f9bf1b1cdd8cd59c34dd915df55e58faf9 100644
--- a/src/briar/gtk/containers/startup.py
+++ b/src/briar/gtk/containers/startup.py
@@ -5,14 +5,17 @@
 from gi.repository import GLib
 
 from briar.gtk.container import Container
-from briar.gtk.define import App
+from briar.gtk.define import APP
 
 
 class StartupContainer(Container):
 
+    SETUP_UI = "/app/briar/gtk/ui/main.ui"
+    LOGIN_UI = "/app/briar/gtk/ui/login.ui"
+
     def __init__(self):
         super().__init__()
-        self._api = App().api
+        self._api = APP().api
         self._setup_view()
 
     # pylint: disable=unused-argument
@@ -39,17 +42,17 @@ class StartupContainer(Container):
     def _setup_view(self):
         self.set_hexpand(True)
         self.set_vexpand(True)
-        if not App().api.has_account():
-            self.builder.add_from_resource("/app/briar/gtk/ui/setup.ui")
+        if not APP().api.has_account():
+            self.builder.add_from_resource(self.SETUP_UI)
             self.add(self.builder.get_object("setup"))
         else:
-            self.builder.add_from_resource("/app/briar/gtk/ui/login.ui")
+            self.builder.add_from_resource(self.LOGIN_UI)
             self.add(self.builder.get_object("login"))
         self.builder.connect_signals(self)
 
     @staticmethod
     def _startup_completed(succeeded):
         if succeeded:
-            GLib.idle_add(App().window.on_startup_completed)
+            GLib.idle_add(APP().window.on_startup_completed)
             return
         print("Startup failed")
diff --git a/src/briar/gtk/define.py b/src/briar/gtk/define.py
index b7d069beaf936cc76c9b1d69042b1d33febadf57..59051148bc288a755d11e9dae7421ec1255f32ad 100644
--- a/src/briar/gtk/define.py
+++ b/src/briar/gtk/define.py
@@ -13,4 +13,4 @@ APPLICATION_NAME = "Briar"
 APPLICATION_STYLING = "resource:///app/briar/gtk/ui/application.css"
 BRIAR_HEADLESS_JAR = "/app/briar/briar-headless.jar"
 
-App = Gio.Application.get_default  # pylint: disable=invalid-name
+APP = Gio.Application.get_default
diff --git a/src/briar/gtk/window.py b/src/briar/gtk/window.py
index 2229dc7a36a9ef6b16c9502bcdf81fc3a935fba1..13cc9eec574f1ca90fff3cd20fe994974f8a1c81 100644
--- a/src/briar/gtk/window.py
+++ b/src/briar/gtk/window.py
@@ -7,7 +7,7 @@ from gi.repository import Gtk
 from briar.gtk.containers.chat import ChatContainer
 from briar.gtk.containers.main import MainContainer
 from briar.gtk.containers.startup import StartupContainer
-from briar.gtk.define import App, APPLICATION_ID, APPLICATION_NAME
+from briar.gtk.define import APP, APPLICATION_ID, APPLICATION_NAME
 from briar.gtk.toolbar import Toolbar
 
 
@@ -28,7 +28,7 @@ class Window(Gtk.ApplicationWindow):
         return self._toolbar
 
     def _initialize_gtk_application_window(self):
-        Gtk.ApplicationWindow.__init__(self, application=App(),
+        Gtk.ApplicationWindow.__init__(self, application=APP(),
                                        title=APPLICATION_NAME,
                                        icon_name=APPLICATION_ID)