diff --git a/crates/clawhdf5/tests/v4_chunk_index_selection.rs b/crates/clawhdf5/tests/v4_chunk_index_selection.rs
index 97cc7c9..23786bd 100644
--- a/crates/clawhdf5/tests/v4_chunk_index_selection.rs
+++ b/crates/clawhdf5/tests/v4_chunk_index_selection.rs
@@ -122,7 +122,10 @@ const CASES: &[Case] = &[
 
 /// `(start, stride, count, block)` per dimension; the first few stay below
 /// half the dataset (bounding-box path), the rest exceed it (full path).
-fn selections() -> Vec<([u64; 2], [u64; 2], [u64; 2], [u64; 2])> {
+/// `(start, stride, count, block)` of a 2-D hyperslab.
+type Hyperslab2 = ([u64; 2], [u64; 2], [u64; 2], [u64; 2]);
+
+fn selections() -> Vec<Hyperslab2> {
     vec![
         ([0, 0], [1, 1], [3, 23], [1, 1]),  // ds[0:3]
         ([7, 3], [1, 1], [9, 6], [1, 1]),   // interior window across chunks
@@ -220,8 +223,10 @@ fn partial_hyperslabs_of_every_v4_chunk_index_match_h5py() {
                 .read_selection(&sel)
                 .unwrap_or_else(|e| panic!("{}: read_selection {sel:?} failed: {e}", case.name));
             let got: Vec<i32> = raw
-                .chunks_exact(4)
-                .map(|b| i32::from_le_bytes(b.try_into().unwrap()))
+                .as_chunks::<4>()
+                .0
+                .iter()
+                .map(|b| i32::from_le_bytes(*b))
                 .collect();
             assert_eq!(got, want, "{}: selection {sel:?}", case.name);
             assert_eq!(