diff --git a/xarray/core/coordinates.py b/xarray/core/coordinates.py
index 85a9d97abeb..f46ff480375 100644
--- a/xarray/core/coordinates.py
+++ b/xarray/core/coordinates.py
@@ -194,7 +194,7 @@ def to_index(self, ordered_dims: Sequence[Hashable] | None = None) -> pd.Index:
 
         return pd.MultiIndex(
             levels=level_list,  # type: ignore[arg-type,unused-ignore]
-            codes=[list(c) for c in code_list],
+            codes=code_list,
             names=names,
         )