diff --git a/grace/grace.go b/grace/grace.go
index b066a639..40eef144 100644
--- a/grace/grace.go
+++ b/grace/grace.go
@@ -86,23 +86,25 @@ var (
 
 	isChild     bool
 	socketOrder string
+	once sync.Once=sync.Once{}
 )
 
 func init() {
+	DefaultMaxHeaderBytes = 0
+	DefaultTimeout = 60 * time.Second
+}
+func onceInit(){
 	regLock = &sync.Mutex{}
 	flag.BoolVar(&isChild, "graceful", false, "listen on open fd (after forking)")
 	flag.StringVar(&socketOrder, "socketorder", "", "previous initialization order - used when more than one listener was started")
 	runningServers = make(map[string]*Server)
 	runningServersOrder = []string{}
 	socketPtrOffsetMap = make(map[string]uint)
-
-	DefaultMaxHeaderBytes = 0
-
-	DefaultTimeout = 60 * time.Second
 }
 
 // NewServer returns a new graceServer.
 func NewServer(addr string, handler http.Handler) (srv *Server) {
+	once.Do(onceInit)
 	regLock.Lock()
 	defer regLock.Unlock()
 	if !flag.Parsed() {