diff --git a/src/App/Service/SZEPManagerService.php b/src/App/Service/SZEPManagerService.php
index 360d218..eaa88d6 100644
--- a/src/App/Service/SZEPManagerService.php
+++ b/src/App/Service/SZEPManagerService.php
@@ -215,7 +215,7 @@ class SZEPManagerService
      * @return string
      * @throws Exception
      */
-    private function getTransactions(): ?string
+    private function getTransactions()
     {
         $appToken = $this->getMobileApplicationToken();
         $authToken = $this->getAuthToken($appToken);