diff --git a/src/tree.rs b/src/tree.rs
index 6b31896..d7e2d68 100644
--- a/src/tree.rs
+++ b/src/tree.rs
@@ -205,13 +205,14 @@ where
         let root_key = Key(0, 0);
 
         subtree.insert(root_key, self.root);
-        self.fill_nodes(root_key, self.next_index, end, &mut subtree)?;
-
-        ////// TODO! Refactor later
-        for i in self.next_index..end {
-            subtree.insert(Key(self.depth, i), leaves[i - self.next_index]);
-        }
-        //////
+        self.fill_nodes(
+            root_key,
+            self.next_index,
+            end,
+            &mut subtree,
+            leaves,
+            self.next_index,
+        )?;
 
         let subtree = Arc::new(RwLock::new(subtree));
 
@@ -248,8 +249,11 @@ where
         start: usize,
         end: usize,
         subtree: &mut HashMap<Key, H::Fr>,
+        leaves: &[H::Fr],
+        from: usize,
     ) -> Result<()> {
         if key.0 == self.depth {
+            subtree.insert(key, leaves[key.1 - from]);
             return Ok(());
         }
 
@@ -265,11 +269,11 @@ where
         let half = 1 << (self.depth - key.0 - 1);
 
         if start < half {
-            self.fill_nodes(left, start, min(end, half), subtree)?;
+            self.fill_nodes(left, start, min(end, half), subtree, leaves, from)?;
         }
 
         if end > half {
-            self.fill_nodes(right, 0, end - half, subtree)?;
+            self.fill_nodes(right, 0, end - half, subtree, leaves, from)?;
         }
 
         Ok(())
diff --git a/tests/sled_keccak.rs b/tests/sled_keccak.rs
index 8c2b253..9eae448 100644
--- a/tests/sled_keccak.rs
+++ b/tests/sled_keccak.rs
@@ -129,7 +129,7 @@ fn insert_delete() -> Result<()> {
 
 #[test]
 fn batch_insertions() -> Result<()> {
-    let mut mt = MerkleTree::<MySled, MyKeccak>::new(2, "abacabas")?;
+    let mut mt = MerkleTree::<MySled, MyKeccak>::new(2, "abacabasa")?;
 
     let leaves = [
         hex!("0000000000000000000000000000000000000000000000000000000000000001"),
@@ -145,7 +145,7 @@ fn batch_insertions() -> Result<()> {
         hex!("a9bb8c3f1f12e9aa903a50c47f314b57610a3ab32f2d463293f58836def38d36")
     );
 
-    fs::remove_dir_all("abacabas").expect("Error removing db");
+    fs::remove_dir_all("abacabasa").expect("Error removing db");
 
     Ok(())
 }