diff --git a/extern.go b/extern.go
index b1d0aff..4d1df25 100644
--- a/extern.go
+++ b/extern.go
@@ -24,7 +24,9 @@ func go_send(s *C.char) {
 	}
 
 	if out.Keychar != CharUndefined {
+		lck.Lock()
 		raw2key[out.Rawcode] = string([]rune{out.Keychar})
+		lck.Unlock()
 	}
 
 	// todo bury this deep into the C lib so that the time is correct
diff --git a/hook.go b/hook.go
index 00927b4..ad29a47 100644
--- a/hook.go
+++ b/hook.go
@@ -26,6 +26,7 @@ import "C"
 
 import (
 	"fmt"
+	"sync"
 	"time"
 	"unsafe"
 )
@@ -83,6 +84,8 @@ type Event struct {
 var (
 	ev      = make(chan Event, 1024)
 	asyncon = false
+
+	lck sync.RWMutex
 )
 
 // String return hook kind string
@@ -136,6 +139,9 @@ func (e Event) String() string {
 
 // RawcodetoKeychar rawcode to keychar
 func RawcodetoKeychar(r uint16) string {
+	lck.RLock()
+	defer lck.RUnlock()
+
 	return raw2key[r]
 }