diff --git a/src/backends/meta-monitor-manager.c b/src/backends/meta-monitor-manager.c
index 3c27edc1a..0cc8a10ef 100644
--- a/src/backends/meta-monitor-manager.c
+++ b/src/backends/meta-monitor-manager.c
@@ -1849,7 +1849,7 @@ meta_monitor_manager_handle_get_resources (MetaDBusDisplayConfig *skeleton,
   g_list_free (combined_outputs);
   g_list_free (combined_crtcs);
 
-  return TRUE;
+  return G_DBUS_METHOD_INVOCATION_HANDLED;
 }
 
 static void
@@ -2182,7 +2182,7 @@ meta_monitor_manager_handle_get_current_state (MetaDBusDisplayConfig *skeleton,
     g_variant_builder_end (&logical_monitors_builder),
     g_variant_builder_end (&properties_builder));
 
-  return TRUE;
+  return G_DBUS_METHOD_INVOCATION_HANDLED;
 }
 
 #undef MODE_FORMAT
@@ -2672,7 +2672,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_ACCESS_DENIED,
                                              "The requested configuration is based on stale information");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   config_store =
@@ -2684,7 +2684,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_ACCESS_DENIED,
                                              "Monitor configuration via D-Bus is disabled");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   capabilities = meta_monitor_manager_get_capabilities (manager);
@@ -2709,7 +2709,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_INVALID_ARGS,
                                              "Can't set layout mode");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   if (!is_valid_layout_mode (layout_mode))
@@ -2717,7 +2717,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_ACCESS_DENIED,
                                              "Invalid layout mode specified");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   g_variant_iter_init (&logical_monitor_configs_iter,
@@ -2746,7 +2746,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
           g_error_free (error);
           g_list_free_full (logical_monitor_configs,
                             (GDestroyNotify) meta_logical_monitor_config_free);
-          return TRUE;
+          return G_DBUS_METHOD_INVOCATION_HANDLED;
         }
 
       logical_monitor_configs = g_list_append (logical_monitor_configs,
@@ -2764,7 +2764,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
                                              "%s", error->message);
       g_error_free (error);
       g_object_unref (config);
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   if (!meta_monitor_manager_is_config_applicable (manager, config, &error))
@@ -2774,7 +2774,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
                                              "%s", error->message);
       g_error_free (error);
       g_object_unref (config);
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   if (method != META_MONITORS_CONFIG_METHOD_VERIFY)
@@ -2793,7 +2793,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
                                              "%s", error->message);
       g_error_free (error);
       g_object_unref (config);
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   if (method == META_MONITORS_CONFIG_METHOD_PERSISTENT)
@@ -2801,7 +2801,7 @@ meta_monitor_manager_handle_apply_monitors_config (MetaDBusDisplayConfig *skelet
 
   meta_dbus_display_config_complete_apply_monitors_config (skeleton, invocation);
 
-  return TRUE;
+  return G_DBUS_METHOD_INVOCATION_HANDLED;
 }
 
 #undef MONITOR_MODE_SPEC_FORMAT
@@ -2848,7 +2848,7 @@ meta_monitor_manager_handle_change_backlight  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_ACCESS_DENIED,
                                              "The requested configuration is based on stale information");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   combined_outputs = combine_gpu_lists (manager, meta_gpu_get_outputs);
@@ -2859,7 +2859,7 @@ meta_monitor_manager_handle_change_backlight  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_INVALID_ARGS,
                                              "Invalid output id");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
   output = g_list_nth_data (combined_outputs, output_index);
   g_list_free (combined_outputs);
@@ -2869,7 +2869,7 @@ meta_monitor_manager_handle_change_backlight  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_INVALID_ARGS,
                                              "Invalid backlight value");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   output_info = meta_output_get_info (output);
@@ -2880,7 +2880,7 @@ meta_monitor_manager_handle_change_backlight  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_INVALID_ARGS,
                                              "Output does not support changing backlight");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   META_MONITOR_MANAGER_GET_CLASS (manager)->change_backlight (manager, output, value);
@@ -2889,7 +2889,7 @@ meta_monitor_manager_handle_change_backlight  (MetaDBusDisplayConfig *skeleton,
   meta_dbus_display_config_complete_change_backlight (skeleton,
                                                       invocation,
                                                       new_backlight);
-  return TRUE;
+  return G_DBUS_METHOD_INVOCATION_HANDLED;
 }
 
 static gboolean
@@ -2910,7 +2910,7 @@ meta_monitor_manager_handle_get_crtc_gamma  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_ACCESS_DENIED,
                                              "The requested configuration is based on stale information");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   combined_crtcs = combine_gpu_lists (manager, meta_gpu_get_crtcs);
@@ -2920,7 +2920,7 @@ meta_monitor_manager_handle_get_crtc_gamma  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_INVALID_ARGS,
                                              "Invalid crtc id");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   crtc = g_list_nth_data (combined_crtcs, crtc_id);
@@ -2946,7 +2946,7 @@ meta_monitor_manager_handle_get_crtc_gamma  (MetaDBusDisplayConfig *skeleton,
   g_bytes_unref (green_bytes);
   g_bytes_unref (blue_bytes);
 
-  return TRUE;
+  return G_DBUS_METHOD_INVOCATION_HANDLED;
 }
 
 static gboolean
@@ -2970,7 +2970,7 @@ meta_monitor_manager_handle_set_crtc_gamma  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_ACCESS_DENIED,
                                              "The requested configuration is based on stale information");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   combined_crtcs = combine_gpu_lists (manager, meta_gpu_get_crtcs);
@@ -2981,7 +2981,7 @@ meta_monitor_manager_handle_set_crtc_gamma  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_INVALID_ARGS,
                                              "Invalid crtc id");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   crtc = g_list_nth_data (combined_crtcs, crtc_id);
@@ -3003,7 +3003,7 @@ meta_monitor_manager_handle_set_crtc_gamma  (MetaDBusDisplayConfig *skeleton,
   g_bytes_unref (green_bytes);
   g_bytes_unref (blue_bytes);
 
-  return TRUE;
+  return G_DBUS_METHOD_INVOCATION_HANDLED;
 }
 
 static gboolean
@@ -3025,7 +3025,7 @@ meta_monitor_manager_handle_set_output_ctm  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_ACCESS_DENIED,
                                              "The requested configuration is based on stale information");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   combined_outputs = combine_gpu_lists (manager, meta_gpu_get_outputs);
@@ -3036,7 +3036,7 @@ meta_monitor_manager_handle_set_output_ctm  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_INVALID_ARGS,
                                              "Invalid output id");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   output = g_list_nth_data (combined_outputs, output_id);
@@ -3047,7 +3047,7 @@ meta_monitor_manager_handle_set_output_ctm  (MetaDBusDisplayConfig *skeleton,
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
                                              G_DBUS_ERROR_INVALID_ARGS,
                                              "Unexpected color transform matrix variant length");
-      return TRUE;
+      return G_DBUS_METHOD_INVOCATION_HANDLED;
     }
 
   for (i = 0; i < 9; i++)
@@ -3062,7 +3062,7 @@ meta_monitor_manager_handle_set_output_ctm  (MetaDBusDisplayConfig *skeleton,
     klass->set_output_ctm (output, &ctm);
   meta_dbus_display_config_complete_set_output_ctm (skeleton, invocation);
 
-  return TRUE;
+  return G_DBUS_METHOD_INVOCATION_HANDLED;
 }
 
 static void