diff --git a/cf_xarray/accessor.py b/cf_xarray/accessor.py
index 7775582d..36a65c34 100644
--- a/cf_xarray/accessor.py
+++ b/cf_xarray/accessor.py
@@ -537,7 +537,7 @@ def _get_coords(obj: DataArray | Dataset, key: Hashable) -> list[Hashable]:
 def _variables(func: F) -> F:
     @functools.wraps(func)
     def wrapper(obj: DataArray | Dataset, key: Hashable) -> list[DataArray]:
-        return [obj[k] for k in func(obj, key)]  # type: ignore[misc]
+        return [obj[k] for k in func(obj, key)]
 
     return cast(F, wrapper)
 
diff --git a/cf_xarray/parametric.py b/cf_xarray/parametric.py
index 06b3d7fd..ca8a85ae 100644
--- a/cf_xarray/parametric.py
+++ b/cf_xarray/parametric.py
@@ -409,7 +409,7 @@ def computed_standard_name(self) -> str:
         ):
             out_stdname = "height_above_geopotential_datum"
         else:
-            raise ValueError(f"Unknown standard name: {out_stdname!r}")
+            raise ValueError(f"Unknown standard name: {ztop_stdname!r}")
 
         return out_stdname