diff --git a/xarray/core/variable.py b/xarray/core/variable.py
index bb988392f50..8cf46c4b88a 100644
--- a/xarray/core/variable.py
+++ b/xarray/core/variable.py
@@ -403,8 +403,8 @@ def nbytes(self) -> int:
         If the underlying data array does not include ``nbytes``, estimates
         the bytes consumed based on the ``size`` and ``dtype``.
         """
-        if hasattr(self.data, "nbytes"):
-            return self.data.nbytes
+        if hasattr(self._data, "nbytes"):
+            return self._data.nbytes
         else:
             return self.size * self.dtype.itemsize