diff --git a/php/AuthSCHClient.class.php b/php/AuthSCHClient.class.php
index 099f9858c2eb3f8e3982881e4778315df3fa9461..37ab9aaf22af9ad586c3af224a81c561cbe982ec 100644
--- a/php/AuthSCHClient.class.php
+++ b/php/AuthSCHClient.class.php
@@ -23,8 +23,10 @@ class AuthSCHClient {
                 
                 // get tokens from auth.sch.bme.hu
                 $this->authenticate();
-                //save tokendata to session
-                $_SESSION['tokens'] = serialize($this->tokens);
+                
+                //save tokendata to session (if we did authentication -> we have refresh token)
+                if(isset($this->tokens->refresh_token))
+                    $_SESSION['tokens'] = serialize($this->tokens);
             } else {
                 // load tokendata from session
                 $this->tokens = unserialize($_SESSION['tokens']);