--- a/toolkit/mozapps/update/updater/progressui_gtk.cpp
+++ b/toolkit/mozapps/update/updater/progressui_gtk.cpp
@@ -93,17 +93,23 @@ ShowProgressUI()
   gtk_window_set_position(GTK_WINDOW(sWin), GTK_WIN_POS_CENTER_ALWAYS);
   gtk_window_set_resizable(GTK_WINDOW(sWin), FALSE);
   gtk_window_set_decorated(GTK_WINDOW(sWin), TRUE);
   gtk_window_set_deletable(GTK_WINDOW(sWin),FALSE);
   pixbuf = gdk_pixbuf_new_from_file (icon_path, nullptr);
   gtk_window_set_icon(GTK_WINDOW(sWin), pixbuf);
   g_object_unref(pixbuf);
 
+#if GTK_CHECK_VERSION(3, 0, 0)
+  GtkWidget *vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 6);
+  gtk_box_set_homogeneous(GTK_BOX(vbox), TRUE);
+#else
   GtkWidget *vbox = gtk_vbox_new(TRUE, 6);
+#endif
+
   sLabel = gtk_label_new(strings.info);
   gtk_misc_set_alignment(GTK_MISC(sLabel), 0.0f, 0.0f);
   sProgressBar = gtk_progress_bar_new();
 
   gtk_box_pack_start(GTK_BOX(vbox), sLabel, FALSE, FALSE, 0);
   gtk_box_pack_start(GTK_BOX(vbox), sProgressBar, TRUE, TRUE, 0);
 
   sTimerID = g_timeout_add(TIMER_INTERVAL, UpdateDialog, nullptr);