diff --git a/pdu/submit.go b/pdu/submit.go
index dcea9b5..b7b8775 100644
--- a/pdu/submit.go
+++ b/pdu/submit.go
@@ -105,7 +105,6 @@ func (p *SUBMIT_SM) Encode(buf *bytes.Buffer) error {
 		return err
 	}
 	buf.Write(encodedMsg)
-	buf.Write(NULL_ARR)
 	return nil
 }
 func (p *SUBMIT_SM) Decode(buf *bytes.Buffer) error {