diff --git a/router/crypto.go b/router/crypto.go
index 12b7735f..38ce4ec0 100644
--- a/router/crypto.go
+++ b/router/crypto.go
@@ -476,7 +476,7 @@ func (sender *EncryptedTCPSender) Send(msg []byte) error {
 	if err != nil {
 		return err
 	}
-	sender.msgCount += sender.msgCount
+	sender.msgCount += 1
 	return sender.outerEncoder.Encode(EncryptPrefixNonce(buffer.Bytes(), &nonce, sender.sessionKey))
 }
 
@@ -531,6 +531,6 @@ func (receiver *EncryptedTCPReceiver) Decode(msg []byte) ([]byte, error) {
 	if wrappedMsg.Number != receiver.msgCount {
 		return msg, fmt.Errorf("Received TCP message with wrong sequence number; possible replay attack")
 	}
-	receiver.msgCount += receiver.msgCount
+	receiver.msgCount += 1
 	return wrappedMsg.Body, nil
 }