diff --git a/src/fairchem/core/datasets/base_dataset.py b/src/fairchem/core/datasets/base_dataset.py
index 2ca26596c..fd0aca5a1 100644
--- a/src/fairchem/core/datasets/base_dataset.py
+++ b/src/fairchem/core/datasets/base_dataset.py
@@ -109,7 +109,9 @@ def _metadata(self) -> DatasetMetadata:
                 for field in DatasetMetadata._fields
             }
         )
-
+        assert np.issubdtype(
+            metadata.natoms.dtype, np.integer
+        ), f"Metadata natoms must be an integer type! not {metadata.natoms.dtype}"
         assert metadata.natoms.shape[0] == len(
             self
         ), "Loaded metadata and dataset size mismatch."