diff --git a/common/protocol/payload.go b/common/protocol/payload.go
index 03eced677..2f3c72904 100644
--- a/common/protocol/payload.go
+++ b/common/protocol/payload.go
@@ -1,6 +1,6 @@
 package protocol
 
-type TransferType int
+type TransferType byte
 
 const (
 	TransferTypeStream TransferType = 0