diff --git a/Cargo.lock b/Cargo.lock
index ed189b7..f97f6f6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -350,9 +350,9 @@ dependencies = [
 
 [[package]]
 name = "rand"
-version = "0.8.5"
+version = "0.8.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+checksum = "5ca0ecfa931c29007047d1bc58e623ab12e5590e8c7cc53200d5202b69266d8a"
 dependencies = [
  "rand_core",
 ]
diff --git a/src/block.rs b/src/block.rs
index 0deaf5f..ef040fc 100644
--- a/src/block.rs
+++ b/src/block.rs
@@ -549,10 +549,10 @@ mod tests {
     #[test]
     fn decode_tail_round_trip() {
         for n in 1..=3usize {
-            let input: Vec<u8> = (0u8..=255)
-                .step_by(if n == 0 { 1 } else { 256 / n + 1 })
-                .take(n)
-                .collect();
+            // n ∈ {1, 2, 3}; step_by stride spreads `take(n)` samples across
+            // the byte range. `n == 0` would divide-by-zero, but it's
+            // excluded by the loop bounds.
+            let input: Vec<u8> = (0u8..=255).step_by(256 / n + 1).take(n).collect();
             let encoded = base85::encode(&input);
             let mut out = vec![0u8; n];
             decode_tail(encoded.as_bytes(), &mut out, 0).expect("valid encoding");