diff --git a/lenskit/parallel/serialize.py b/lenskit/parallel/serialize.py
index af6eacbd7..debd31891 100644
--- a/lenskit/parallel/serialize.py
+++ b/lenskit/parallel/serialize.py
@@ -77,8 +77,8 @@ def reducer_override(self, obj: Any) -> Any:
                 )
             elif obj.layout == torch.sparse_csc:
                 return torch.sparse_csc_tensor, (
-                    obj.row_indices(),
                     obj.ccol_indices(),
+                    obj.row_indices(),
                     obj.values(),
                     obj.shape,
                 )