diff --git a/rpc/dataconn/stream/stream_conn.go b/rpc/dataconn/stream/stream_conn.go
index 1ab05b0..bcbed6e 100644
--- a/rpc/dataconn/stream/stream_conn.go
+++ b/rpc/dataconn/stream/stream_conn.go
@@ -144,6 +144,7 @@ func (c *Conn) ReadStream(frameType uint32, closeConnOnClose bool) (_ *StreamRea
 
 	c.readMtx.Lock()
 	if !c.readClean {
+		c.readMtx.Unlock()
 		return nil, errWriteStreamToErrorUnknownState
 	}