diff --git a/data/gui/roster_window.ui b/data/gui/roster_window.ui
index f7bd24a56..747720e5c 100644
--- a/data/gui/roster_window.ui
+++ b/data/gui/roster_window.ui
@@ -3,7 +3,7 @@
 <interface>
   <requires lib="gtk+" version="3.12"/>
   <object class="GtkAccelGroup" id="accelgroup1"/>
-  <object class="GtkWindow" id="roster_window">
+  <object class="GtkApplicationWindow" id="roster_window">
     <property name="width_request">85</property>
     <property name="height_request">200</property>
     <property name="can_focus">False</property>
diff --git a/src/roster_window.py b/src/roster_window.py
index 4ca0a644e..b169e0073 100644
--- a/src/roster_window.py
+++ b/src/roster_window.py
@@ -94,7 +94,7 @@ empty_pixbuf = GdkPixbuf.Pixbuf.new(GdkPixbuf.Colorspace.RGB, True, 8, 1, 1)
 empty_pixbuf.fill(0xffffff00)
 
 
-class RosterWindow(Gtk.ApplicationWindow):
+class RosterWindow:
     """
     Class for main window of the GTK+ interface
     """
@@ -6178,7 +6178,7 @@ class RosterWindow(Gtk.ApplicationWindow):
 ###
 ################################################################################
 
-    def __init__(self, app):
+    def __init__(self, app: Gtk.Application):
         self.application = app
         self.filtering = False
         self.starting = False
@@ -6195,8 +6195,8 @@ class RosterWindow(Gtk.ApplicationWindow):
             GdkPixbuf.Pixbuf, GdkPixbuf.Pixbuf]
         self.xml = gtkgui_helpers.get_gtk_builder('roster_window.ui')
         self.window = self.xml.get_object('roster_window')
+        app.add_window(self.window)
         self.hpaned = self.xml.get_object('roster_hpaned')
-        self.window.set_application(app)
         gajim.interface.msg_win_mgr = MessageWindowMgr(self.window, self.hpaned)
         gajim.interface.msg_win_mgr.connect('window-delete',
             self.on_message_window_delete)