diff --git a/weed/util/grace/signal_handling.go b/weed/util/grace/signal_handling.go
index fc7afcad9..24d2b184f 100644
--- a/weed/util/grace/signal_handling.go
+++ b/weed/util/grace/signal_handling.go
@@ -12,7 +12,7 @@ import (
 
 var signalChan chan os.Signal
 var hooks = make([]func(), 0)
-var hookLock sync.Mutex
+var hookLock sync.RWMutex
 
 func init() {
 	signalChan = make(chan os.Signal, 1)
@@ -27,7 +27,9 @@ func init() {
 		// syscall.SIGQUIT,
 	)
 	go func() {
-		for _ = range signalChan {
+		hookLock.RLock()
+		defer hookLock.RUnlock()
+		for range signalChan {
 			for _, hook := range hooks {
 				hook()
 			}