diff --git a/scripts/assemble_changelog.py b/scripts/assemble_changelog.py
index 07e6fc58a..99c97a902 100755
--- a/scripts/assemble_changelog.py
+++ b/scripts/assemble_changelog.py
@@ -350,13 +350,13 @@ def commit_timestamp(commit_id):
         text = subprocess.check_output(['git', 'show', '-s',
                                         '--format=%ct',
                                         commit_id])
-        return datetime.datetime.utcfromtimestamp(int(text))
+        return datetime.datetime.fromtimestamp(int(text), datetime.timezone.utc)
 
     @staticmethod
     def file_timestamp(filename):
         """Return the modification timestamp of the given file."""
         mtime = os.stat(filename).st_mtime
-        return datetime.datetime.fromtimestamp(mtime)
+        return datetime.datetime.fromtimestamp(mtime, datetime.timezone.utc)
 
     def __init__(self, filename):
         """Determine position of the file in the changelog entry order.