diff --git a/dkist/io/asdf/converters/tiled_dataset.py b/dkist/io/asdf/converters/tiled_dataset.py
index 56d9379a..4c3f4907 100644
--- a/dkist/io/asdf/converters/tiled_dataset.py
+++ b/dkist/io/asdf/converters/tiled_dataset.py
@@ -31,5 +31,5 @@ def to_yaml_tree(cls, tiled_dataset, tag, ctx):
         meta.pop("history", None)
         tree["meta"] = meta
         tree["datasets"] = tiled_dataset._data.tolist()
-        tree["mask"] = tiled_dataset._data.mask.tolist()
+        tree["mask"] = tiled_dataset._data.mask
         return tree
diff --git a/dkist/io/asdf/resources/schemas/tiled_dataset-1.2.0.yaml b/dkist/io/asdf/resources/schemas/tiled_dataset-1.2.0.yaml
index ab98bfe2..3d5b1682 100644
--- a/dkist/io/asdf/resources/schemas/tiled_dataset-1.2.0.yaml
+++ b/dkist/io/asdf/resources/schemas/tiled_dataset-1.2.0.yaml
@@ -38,11 +38,7 @@ properties:
 
   mask:
     description: A mask to indicate if invalid or missing Datasets should be ignored.
-    type: array
-    items:
-      type: array
-      items:
-        - type: boolean
+    datatype: bool8
 
 required: [datasets, meta, mask]
 additionalProperties: false