diff --git a/DB/storage.php b/DB/storage.php
index 7b653ed..e25b123 100644
--- a/DB/storage.php
+++ b/DB/storage.php
@@ -251,7 +251,7 @@ function toString()
                     if ($i > 0) {
                         $info .= ",";
                     }
-                    $info .= $this->$keyname[$i];
+                    $info .= $this->{$keyname[$i]};
                 }
                 $info .= ")";
             } else {