diff --git a/access-utils.go b/access-utils.go
index a83b908..95a114d 100644
--- a/access-utils.go
+++ b/access-utils.go
@@ -14,7 +14,7 @@ func (g Groupname) ToString() string {
 // Converts input username object to string representation.
 // Uses the format uid@realm.
 func (u Username) ToString() string {
-	return fmt.Sprintf("%s-%s", u.UserID, u.Realm)
+	return fmt.Sprintf("%s@%s", u.UserID, u.Realm)
 }
 
 // Parses input groupname string to gid and realm.