diff --git a/src/Models/XeroToken.php b/src/Models/XeroToken.php
index 01453c0..18c98e9 100755
--- a/src/Models/XeroToken.php
+++ b/src/Models/XeroToken.php
@@ -31,4 +31,8 @@ protected function expires(): Attribute
             fn(): DateTimeInterface => $this->updated_at->addSeconds($this->expires_in)
         );
     }
+
+    protected $casts = [
+        'expires_in' => 'integer',
+    ];
 }