diff --git a/xarray/coding/variables.py b/xarray/coding/variables.py
index eee2858e074..71bab010a5b 100644
--- a/xarray/coding/variables.py
+++ b/xarray/coding/variables.py
@@ -241,7 +241,7 @@ def encode(self, variable: Variable, name: T_Name = None):
         if isinstance(units, str) and "since" in units:
             encoded_dtype = encoding.pop("dtype")
             if encoded_dtype is not None and encoded_dtype != data.dtype:
-                data = np.asarray(data, dtype=encoded_dtype)
+                data = duck_array_ops.astype(data, encoded_dtype)
 
         if fv_exists:
             # Ensure _FillValue is cast to same dtype as data's