diff --git a/src/device/input/parse/v01/tts.go b/src/device/input/parse/v01/tts.go
index a01eac9..80112b8 100644
--- a/src/device/input/parse/v01/tts.go
+++ b/src/device/input/parse/v01/tts.go
@@ -7,6 +7,7 @@ import (
 	"log"
 	"net/http"
 	"net/url"
+	"sync"
 	"time"
 
 	"github.com/faiface/beep"
@@ -15,6 +16,10 @@ import (
 	"github.com/faiface/beep/wav"
 )
 
+var (
+	ttsLock = &sync.RWMutex{}
+)
+
 func (v01 *V01) tts(text string) {
 	if err := v01._tts(text); err != nil {
 		log.Printf("failed to tts: %s: %v", text, err)
@@ -58,7 +63,11 @@ func (v01 *V01) _tts(text string) error {
 	if err != nil {
 		return err
 	}
+	ttsLock.Lock()
+	defer ttsLock.Unlock()
 	speaker.Init(format.SampleRate, format.SampleRate.N(time.Second/30))
 	speaker.Play(&effects.Volume{Streamer: beep.ResampleRatio(4, 1, &beep.Ctrl{Streamer: beep.Loop(1, decoder)})})
+	duration := time.Duration(decoder.Len()) * format.SampleRate.D(1)
+	time.Sleep(duration)
 	return nil
 }
diff --git a/src/device/input/parse/v01/v01_exported_test.go b/src/device/input/parse/v01/v01_exported_test.go
index b627d53..2a67684 100644
--- a/src/device/input/parse/v01/v01_exported_test.go
+++ b/src/device/input/parse/v01/v01_exported_test.go
@@ -169,7 +169,7 @@ func TestV01Feedback(t *testing.T) {
 			}
 			resp.Body.Close()
 		}
-		time.Sleep(time.Second * 2)
+		time.Sleep(time.Second * 3)
 	})
 }