diff --git a/src/Service/MantisConnector.php b/src/Service/MantisConnector.php
index a2ec87e..b84635f 100644
--- a/src/Service/MantisConnector.php
+++ b/src/Service/MantisConnector.php
@@ -66,7 +66,7 @@ public function patchUpstreamField(MantisIssue $issue): bool
 
         try {
             $this->client->patch(
-                $issue->getId(),
+                (string) $issue->getId(),
                 [
                     'body' => $body,
                 ],