diff --git a/xarray/conventions.py b/xarray/conventions.py
index 2f20cc4c2a4..d2016c6cf67 100644
--- a/xarray/conventions.py
+++ b/xarray/conventions.py
@@ -454,8 +454,8 @@ def stackable(dim: Hashable) -> bool:
                 mask_and_scale=_item_or_default(mask_and_scale, k, True),
                 decode_times=_item_or_default(decode_times, k, True),
                 stack_char_dim=stack_char_dim,
-                use_cftime=_item_or_default(use_cftime, k, True),
-                decode_timedelta=_item_or_default(decode_timedelta, k, True),
+                use_cftime=_item_or_default(use_cftime, k),
+                decode_timedelta=_item_or_default(decode_timedelta, k),
             )
         except Exception as e:
             raise type(e)(f"Failed to decode variable {k!r}: {e}") from e