Forgot to adjust declaration of `now` variable.
diff --git a/gio/gdbusauthmechanismsha1.c b/gio/gdbusauthmechanismsha1.c
index d47221f..0f9e45c 100644
--- a/gio/gdbusauthmechanismsha1.c
+++ b/gio/gdbusauthmechanismsha1.c
@@ -603,7 +603,7 @@
   gchar **lines;
   gint max_line_id;
   GString *new_contents;
-  guint64 now;
+  gint64 now;
   gboolean have_id;
   gint use_id;
   gchar *use_cookie;