diff --git a/id.go b/id.go
index 8e549bc..0b338fb 100644
--- a/id.go
+++ b/id.go
@@ -33,5 +33,5 @@ func (id *IdGenerator) Hash() string {
 	h := md5.New()
 	ns := time.Now().UnixNano() + <-id.id
 	io.WriteString(h, fmt.Sprintf("%d", ns))
-	return fmt.Sprintf("%x", h.Sum(nil))
+	return fmt.Sprintf("%x", h.Sum(nil))[:8]
 }