diff --git a/worker/agent.go b/worker/agent.go
index 5c2b384..659960a 100644
--- a/worker/agent.go
+++ b/worker/agent.go
@@ -200,3 +200,10 @@ func (a *agent) write(outpack *outPack) (err error) {
 	}
 	return a.rw.Flush()
 }
+
+// Write with lock
+func (a *agent) Write(outpack *outPack) (err error) {
+	a.Lock()
+	defer a.Unlock()
+	return a.write(outpack)
+}
diff --git a/worker/worker.go b/worker/worker.go
index c8c91db..25d6a60 100644
--- a/worker/worker.go
+++ b/worker/worker.go
@@ -292,7 +292,7 @@ func (worker *Worker) exec(inpack *inPack) (err error) {
 		}
 		outpack.handle = inpack.handle
 		outpack.data = r.data
-		inpack.a.write(outpack)
+		inpack.a.Write(outpack)
 	}
 	return
 }