diff --git a/py-polars/polars/series/series.py b/py-polars/polars/series/series.py
index f532de9011b4..506c52ed9f7a 100644
--- a/py-polars/polars/series/series.py
+++ b/py-polars/polars/series/series.py
@@ -1019,11 +1019,8 @@ def _arithmetic(self, other: Any, op_s: str, op_ffi: str) -> Self:
             else:
                 return self._from_pyseries(getattr(self._s, op_s)(_s))
         else:
-            dtype = self.dtype
-            while hasattr(dtype, "inner"):
-                dtype = dtype.inner
-            other = maybe_cast(other, dtype)
-            f = get_ffi_func(op_ffi, dtype, self._s)
+            other = maybe_cast(other, self.dtype)
+            f = get_ffi_func(op_ffi, self.dtype, self._s)
         if f is None:
             msg = (
                 f"cannot do arithmetic with Series of dtype: {self.dtype!r} and argument"