diff --git a/simple_repository_browser/fetch_description.py b/simple_repository_browser/fetch_description.py
index c49a8a6..2ad2e49 100644
--- a/simple_repository_browser/fetch_description.py
+++ b/simple_repository_browser/fetch_description.py
@@ -192,14 +192,6 @@ async def _fetch_metadata_resource(
     if isinstance(resource, model.TextResource):
         with open(tmp_file_path, "wb") as tmp:
             tmp.write(resource.text.encode())
-        if not file.upload_time:
-            # If the repository doesn't provide information about the upload time, estimate
-            # it from the headers of the resource, if they exist.
-            if ct := resource.context.get("creation-date"):
-                if isinstance(ct, str):
-                    file = dataclasses.replace(
-                        file, upload_time=datetime.datetime.fromisoformat(ct)
-                    )
     elif isinstance(resource, model.HttpResource):
         await fetch_file(resource.url, tmp_file_path)
     else:
diff --git a/simple_repository_browser/short_release_info.py b/simple_repository_browser/short_release_info.py
index 26390b4..08b8f53 100644
--- a/simple_repository_browser/short_release_info.py
+++ b/simple_repository_browser/short_release_info.py
@@ -1,5 +1,5 @@
 import dataclasses
-from datetime import datetime
+from datetime import datetime, timezone
 import functools
 import types
 import typing
@@ -135,9 +135,12 @@ def release_infos(
             quarantined_file: Quarantinefile = {
                 "filename": file_info["filename"],
                 "quarantine_release_time": datetime.strptime(
-                    file_info["quarantine_release_time"], date_format
-                ),
-                "upload_time": datetime.strptime(file_info["upload_time"], date_format),
+                    file_info["quarantine_release_time"],
+                    date_format,
+                ).replace(tzinfo=timezone.utc),
+                "upload_time": datetime.strptime(
+                    file_info["upload_time"], date_format
+                ).replace(tzinfo=timezone.utc),
             }
             version_str = None
             try: