diff --git a/metadapta.go b/metadapta.go
index 41ce59d..8250478 100644
--- a/metadapta.go
+++ b/metadapta.go
@@ -66,18 +66,21 @@ func (this *a) RemoteAddr() net.Addr {
 func (this *a) OpenTrans() (Trans, error) {
 	this.transLock.Lock()
 	defer this.transLock.Unlock()
+	if this.transID == int64Max {
+		return nil, fmt.Errorf("could not open transaction: %w", ErrIntegerOverflow)
+	}
 	id := this.transID
-	this.transID ++
 	trans := &transA {
 		parent:   this,
 		id:       id,
 		incoming: usync.NewGate[incomingMessage](),
 	}
 	this.transMap[id] = trans
-	if this.transID == int64Max {
-		return nil, fmt.Errorf("could not open transaction: %w", ErrIntegerOverflow)
+	if this.party == ClientSide {
+		this.transID ++
+	} else {
+		this.transID --
 	}
-	this.transID ++
 	return trans, nil
 }