diff --git a/src/repr.rs b/src/repr.rs
index ccdfbcd..35e4594 100644
--- a/src/repr.rs
+++ b/src/repr.rs
@@ -86,11 +86,10 @@ impl Board {
             .into_iter()
             .map(|range| range.into_iter().map(|i| (i, j)).collect())
             .collect();
-        chains.append(
-            &mut split_from(0, BOARD_SIZE - 1, j)
+        chains.extend(
+            split_from(0, BOARD_SIZE - 1, j)
                 .into_iter()
-                .map(|range| range.into_iter().map(|j| (i, j)).collect())
-                .collect(),
+                .map(|range| range.into_iter().map(|j| (i, j)).collect()),
         );
 
         for chain in chains {