diff --git a/src/CelerisLab/lbm/blocks.py b/src/CelerisLab/lbm/blocks.py
index f0fab2c..8869fe2 100644
--- a/src/CelerisLab/lbm/blocks.py
+++ b/src/CelerisLab/lbm/blocks.py
@@ -330,7 +330,8 @@ class BlockLayout2D:
             raise ValueError("a layout with holes unpacks floating arrays only (holes are NaN)")
         ob, oc = np.divmod(self.owner.ravel()[owned].astype(np.intp), flat.shape[2])
         dense = np.empty((NQ, owned.size), dtype=blocked.dtype)
-        dense[:, ~owned] = np.nan
+        if not owned.all():  # even an empty NaN assignment fails for integer dtypes
+            dense[:, ~owned] = np.nan
         dense[:, owned] = flat[ob, :, oc].T
         return dense.reshape(NQ, *self.shape)