diff --git a/libselect/src/normal_select.rs b/libselect/src/normal_select.rs
index b84e55d..3389cfd 100644
--- a/libselect/src/normal_select.rs
+++ b/libselect/src/normal_select.rs
@@ -112,9 +112,13 @@ impl NormalSelect {
         }
     }
 
-    pub fn select_k(&mut self, list: &mut Vec<u64>, order_statistic: usize, k: usize) -> u64 {
+    pub fn select_k_mut(&mut self, list: &mut Vec<u64>, order_statistic: usize, k: usize) -> u64 {
         self._select(list, 0, list.len() - 1, order_statistic, k).1
     }
+    pub fn select_k(&mut self, list: &Vec<u64>, order_statistic: usize, k: usize) -> u64 {
+        let mut list_clone = list.clone();
+        self._select(&mut list_clone, 0, list.len() - 1, order_statistic, k).1
+    }
 }
 
 impl Select for NormalSelect {
@@ -128,7 +132,7 @@ impl Select for NormalSelect {
     }
 
     fn select_mut(&mut self, list: &mut Vec<u64>, order_statistic: usize) -> u64 {
-        self.select_k(list, order_statistic, 5)
+        self.select_k_mut(list, order_statistic, 5)
     }
 
     fn num_comp(&self) -> u64 {