diff --git a/gio/gsettings-tool.c b/gio/gsettings-tool.c
index c7df95910..3f7d478ab 100644
--- a/gio/gsettings-tool.c
+++ b/gio/gsettings-tool.c
@@ -213,7 +213,7 @@ handle_set (gint   *argc,
       goto out;
     }
 
-  g_settings_sync (NULL);
+  g_settings_sync ();
   ret = 0;
 
  out:
diff --git a/gio/gsettings.h b/gio/gsettings.h
index 290f02a38..f98ecc6d0 100644
--- a/gio/gsettings.h
+++ b/gio/gsettings.h
@@ -134,7 +134,7 @@ void                    g_settings_delay                                (GSettin
 void                    g_settings_apply                                (GSettings          *settings);
 void                    g_settings_revert                               (GSettings          *settings);
 gboolean                g_settings_get_has_unapplied                    (GSettings          *settings);
-void                    g_settings_sync                                 ();
+void                    g_settings_sync                                 (void);
 
 /**
  * GSettingsBindSetMapping: