--- gnome-settings-daemon-3.26.1/data/gsd-enums.h   2015-11-10 09:07:12.000000000 -0500
+++ gnome-settings-daemon-3.26.1/data/gsd-enums.h   2015-11-11 18:43:43.240794875 -0500
@@ -105,6 +105,7 @@
 typedef enum
 {
   GSD_POWER_BUTTON_ACTION_NOTHING,
+  GSD_POWER_BUTTON_ACTION_SHUTDOWN,
   GSD_POWER_BUTTON_ACTION_SUSPEND,
   GSD_POWER_BUTTON_ACTION_HIBERNATE,
   GSD_POWER_BUTTON_ACTION_INTERACTIVE

--- gnome-settings-daemon-3.26.1/plugins/media-keys/gsd-media-keys-manager.c    2015-11-10 09:07:12.000000000 -0500
+++ gnome-settings-daemon-3.26.1/plugins/media-keys/gsd-media-keys-manager.c    2015-11-11 18:47:52.388602012 -0500
@@ -1954,6 +1849,9 @@

         action_type = g_settings_get_enum (manager->priv->power_settings, "power-button-action");
         switch (action_type) {
+        case GSD_POWER_BUTTON_ACTION_SHUTDOWN:
+                do_config_power_action (manager, GSD_POWER_ACTION_SHUTDOWN, in_lock_screen);
+                break;
         case GSD_POWER_BUTTON_ACTION_SUSPEND:
                 do_config_power_action (manager, GSD_POWER_ACTION_SUSPEND, in_lock_screen);
                 break;