diff --git a/src/msgraph_core/tasks/large_file_upload.py b/src/msgraph_core/tasks/large_file_upload.py
index 882b2ad6..eec31c9a 100644
--- a/src/msgraph_core/tasks/large_file_upload.py
+++ b/src/msgraph_core/tasks/large_file_upload.py
@@ -75,7 +75,7 @@ def upload_session_expired(self, upload_session: Optional[Parsable] = None) -> b
         if isinstance(expiry, str):
             then = datetime.strptime(expiry, "%Y-%m-%dT%H:%M:%S")
         elif isinstance(expiry, datetime):
-            then = expiry
+            then = expiry.replace(tzinfo=timezone.utc)
         else:
             raise ValueError("Expiry is not a string or datetime")
         interval = now - then