diff --git a/oml/update.py b/oml/update.py
index 5f7f7fe..10d24e2 100644
--- a/oml/update.py
+++ b/oml/update.py
@@ -621,10 +621,10 @@ def migrate_13():
         with db.session() as session:
             revision = -1
             qs = changelog.Changelog.query.filter_by(user_id=settings.USER_ID)
-            with open(path, 'w') as fd:
+            with open(path, 'wb') as fd:
                 for c in qs.order_by('timestamp'):
-                    data = json.dumps([c.revision, c.timestamp, json.loads(c.data)], ensure_ascii=False)
-                    fd.write(data + '\n')
+                    data = json.dumps([c.revision, c.timestamp, json.loads(c.data)], ensure_ascii=False).encode('utf-8')
+                    fd.write(data + b'\n')
                     revision = c.revision
             if revision > -1:
                 settings.server['revision'] = revision