diff --git a/libselect/src/normal_select.rs b/libselect/src/normal_select.rs
index 41eae30..3378844 100644
--- a/libselect/src/normal_select.rs
+++ b/libselect/src/normal_select.rs
@@ -53,8 +53,8 @@ impl NormalSelect {
         let mut chunks = list.chunks(5)
             .collect::<Vec<_>>();
 
-        for chunk in chunks.iter_mut() {
-            let chunk = self.insertion.sort(&chunk.to_vec());
+        for mut chunk in chunks.iter_mut().map(|c| c.to_vec()) {
+            self.insertion.sort_mut(&mut chunk);
             medians.push(chunk[chunk.len() / 2]);
         }