diff --git a/config.go b/config.go
index 8e9a7c8..3dbfec8 100644
--- a/config.go
+++ b/config.go
@@ -23,7 +23,7 @@ type Config struct {
 	} `yaml:"network"`
 
 	IPv4Nodes map[uint32]string
-	Lock      sync.Mutex
+	lock      sync.Mutex
 }
 
 var config = NewConfig()
@@ -56,3 +56,9 @@ func NewConfig() *Config {
 
 	return cnf
 }
+
+func (cnf *Config) Lock(do func()) {
+	cnf.lock.Lock()
+	defer cnf.lock.Unlock()
+	do()
+}
diff --git a/tap.go b/tap.go
index 103f49a..4035019 100644
--- a/tap.go
+++ b/tap.go
@@ -167,12 +167,15 @@ func (nc *NetCard) runRead() {
 				continue
 			}
 
-			var realAddr string
-			config.Lock.Lock()
-			if _, ok = config.IPv4Nodes[binary.LittleEndian.Uint32([]byte(waterutil.IPv4Destination(rframe)))]; !ok {
+			var realAddr string = ""
+			config.Lock(func() {
+				if realAddr, ok = config.IPv4Nodes[binary.LittleEndian.Uint32([]byte(waterutil.IPv4Destination(rframe)))]; !ok {
+					return
+				}
+			})
+			if realAddr == "" {
 				continue
 			}
-			config.Lock.Unlock()
 
 			// log.Printf("Payload: % x\n", rframe.Payload())