diff --git a/src/SwedbankJson.php b/src/SwedbankJson.php
index 7ea85ac..aadbfe1 100644
--- a/src/SwedbankJson.php
+++ b/src/SwedbankJson.php
@@ -94,6 +94,7 @@ public function __construct($username, $password, $appdata, $debug=false, $ckfil
     public function __destruct()
     {
         $this->terminate();
+        unlink($this->_ckfile);
     }
 
     /**