diff --git a/qubes/storage/reflink.py b/qubes/storage/reflink.py
index 9ff1c06b..7cb9ca10 100644
--- a/qubes/storage/reflink.py
+++ b/qubes/storage/reflink.py
@@ -187,9 +187,9 @@ class ReflinkVolume(qubes.storage.Volume):
         _rename_file(self._path_dirty, self._path_clean)
 
     def _add_revision(self):
-        if self.revisions_to_keep is 0:
+        if self.revisions_to_keep == 0:
             return
-        if _get_file_disk_usage(self._path_clean) is 0:
+        if _get_file_disk_usage(self._path_clean) == 0:
             return
         ctime = os.path.getctime(self._path_clean)
         revision = qubes.storage.isodate(int(ctime)) + 'Z'