diff --git a/delivery_parcelhub_whistl/models/delivery.py b/delivery_parcelhub_whistl/models/delivery.py
index 8d47722..c36b0c9 100644
--- a/delivery_parcelhub_whistl/models/delivery.py
+++ b/delivery_parcelhub_whistl/models/delivery.py
@@ -607,7 +607,7 @@ def whistl_tracking_state_update(self, picking):
             )
 
         try:
-            tracking_response = ET.fromstring(response.content)
+            tracking_response = ET.fromstring(response.content.decode("utf8"))
         except Exception as e:
             raise ValidationError(
                 _(