diff --git a/src/accumulator/pollard.rs b/src/accumulator/pollard.rs
index 40018f7..a399538 100644
--- a/src/accumulator/pollard.rs
+++ b/src/accumulator/pollard.rs
@@ -24,7 +24,7 @@
 //! let p = Pollard::new()
 //!     .modify(&hashes, &[])
 //!     .expect("Simple addition don't fail")
-//!     .modify(&[], &[0, 3])
+//!     .modify(&[], &[hashes[0], hashes[3]])
 //!     .expect("Nor should simple deletion with known to be in tree elements");
 //! // We should get this state after
 //! assert_eq!(p.get_roots().len(), 1);
@@ -70,7 +70,8 @@
 //! mutability, there is a simple specialized function to do the job, and the API gives you
 //! a [Rc] over a node, not the [RefCell], so avoid using the [RefCell] directly.
 use super::node_hash::NodeHash;
-use super::util::{detwin, is_left_niece, is_root_position, tree_rows};
+use super::util::{calc_next_pos, is_left_niece, is_root_position, tree_rows};
+use std::collections::HashMap;
 use std::{cell::Cell, fmt::Debug};
 use std::{cell::RefCell, rc::Rc};
 type Node = Rc<PolNode>;
@@ -113,7 +114,7 @@ impl Debug for PolNode {
             let mut next_nodes = vec![];
             for node in row_nodes {
                 if let Some(node) = node {
-                    write!(f, "{:?} ", &node.get_data()[0..2])?;
+                    write!(f, "{:02x}{:02x} ", node.get_data()[0], node.get_data()[1])?;
 
                     let (l, r) = node.get_children();
                     next_nodes.push(l);
@@ -222,10 +223,7 @@ impl PolNode {
         if let Some(parent) = self.get_parent() {
             return parent.recompute_parent_hash();
         }
-        // It's impossible to reach this, because if we are a branch node (not a leaf), we
-        // will get into the first case, otherwise the second if will be taken.
-        // Leave this unreachable to catch weird bugs
-        unreachable!();
+        return;
     }
     /// Returns this node's aunt as [Node]
     fn get_aunt(&self) -> Option<Node> {
@@ -275,7 +273,7 @@ impl PolNode {
         self.r_niece.replace(r_niece);
     }
     /// Chops down any subtree this node has
-    fn chop(&self) {
+    fn _chop(&self) {
         self.l_niece.replace(None);
         self.r_niece.replace(None);
     }
@@ -290,6 +288,9 @@ pub struct Pollard {
     leaves: u64,
     /// The actual roots
     roots: Vec<Node>,
+    /// Holds a map of all nodes in the tree. This is used to lookup specific nodes on deletion
+    /// and while proving
+    map: HashMap<NodeHash, u64>,
 }
 
 impl Pollard {
@@ -335,7 +336,7 @@ impl Pollard {
     ///        .expect("Pollard should not fail");
     /// assert_eq!(p.get_roots()[0].get_data().to_string(), String::from("b151a956139bb821d4effa34ea95c17560e0135d1e4661fc23cedc3af49dac42"));
     /// ```
-    pub fn modify(self, utxos: &[NodeHash], stxos: &[u64]) -> Result<Pollard, String> {
+    pub fn modify(self, utxos: &[NodeHash], stxos: &[NodeHash]) -> Result<Pollard, String> {
         let acc = self.delete(stxos)?.add(utxos);
 
         Ok(acc)
@@ -357,27 +358,49 @@ impl Pollard {
 
         // If deleting a root, we just place a default node in it's place
         if is_root_position(pos, self.leaves, tree_rows(self.leaves)) {
+            self.map.remove_entry(&self.roots[tree as usize].get_data());
             self.roots[tree as usize] = PolNode::default().into_rc();
             return Ok(());
         }
         // Grab the node we'll move up
         // from_node is whomever is moving up, to node is the position it will be
         // after moved
-        let (from_node, _, to_node) = self.grab_node(pos)?;
+        let (from_node, del, to_node) = self.grab_node(pos)?;
         // If the position I'm moving to has an aunt, I'm not becoming a root.
         // ancestor is the node right beneath the to_node, this is useful because
         // either it or it's sibling points to the `to_node`. We need to update this.
+        // let new_pos = parent(pos, tree_rows(self.leaves));
+        self.map.remove_entry(&del.get_data());
+        self.update_positions(&from_node, pos)?;
         if let Some(sibling) = to_node.get_sibling() {
             // If my new ancestor has a sibling, it means my aunt/parent is not root
             // and my aunt is pointing to me, *not* my parent.
-            sibling.chop();
+            sibling.set_nieces(del.get_l_niece(), del.get_r_niece());
+            if let Some(n) = sibling.get_l_niece() {
+                n.set_aunt(Some(sibling.clone()));
+            }
+            if let Some(n) = sibling.get_r_niece() {
+                n.set_aunt(Some(sibling.clone()));
+            }
             to_node.set_self_hash(from_node.get_data());
-            to_node.set_nieces(to_node.get_l_niece(), to_node.get_r_niece());
+            if let Some(n) = to_node.get_l_niece() {
+                n.set_aunt(Some(to_node.clone()));
+            }
+            if let Some(n) = to_node.get_r_niece() {
+                n.set_aunt(Some(to_node.clone()));
+            }
             to_node.recompute_parent_hash();
         } else {
             // This means we are a root's sibling. We are becoming a root now
             to_node.set_self_hash(from_node.get_data());
-            to_node.set_nieces(from_node.get_l_niece(), from_node.get_l_niece());
+            to_node.set_nieces(del.get_l_niece(), del.get_r_niece());
+            if let Some(n) = to_node.get_l_niece() {
+                n.set_aunt(Some(to_node.clone()));
+            }
+            if let Some(n) = to_node.get_r_niece() {
+                n.set_aunt(Some(to_node.clone()));
+            }
+            to_node.recompute_parent_hash();
         }
         Ok(())
     }
@@ -417,20 +440,56 @@ impl Pollard {
     fn add(mut self, utxos: &[NodeHash]) -> Self {
         for utxo in utxos {
             self.roots = Pollard::add_single(self.roots, *utxo, self.leaves);
+            self.map.insert(*utxo, self.leaves);
             self.leaves += 1;
         }
 
         self
     }
     /// Deletes nodes from the accumulator
-    fn delete(mut self, stxos: &[u64]) -> Result<Self, String> {
-        let stxos = detwin(stxos.to_vec(), tree_rows(self.leaves));
+    fn delete(mut self, stxos: &[NodeHash]) -> Result<Self, String> {
         for stxo in stxos.iter() {
-            self.delete_single(*stxo)?;
+            let pos = self
+                .map
+                .get(stxo)
+                .ok_or(format!("UTXO {} is not in the forest", stxo))?;
+            if let Err(e) = self.delete_single(*pos) {
+                return Err(e);
+            }
         }
 
         Ok(self)
     }
+    fn update_positions(&mut self, node: &Node, del_pos: u64) -> Result<(), String> {
+        let mut to_remap = vec![];
+        let forest_rows = tree_rows(self.leaves);
+        to_remap.push(node.to_owned());
+        while !to_remap.is_empty() {
+            let next = to_remap.pop().expect("We checked this is not empty");
+            let (l_child, r_child) = next.get_children();
+            if let (Some(l_child), Some(r_child)) = (l_child, r_child) {
+                to_remap.push(l_child);
+                to_remap.push(r_child);
+                continue;
+            } else {
+                let pos = self.map.get(&next.get_data()).ok_or(format!(
+                    "Node with hash {} is not in the tree",
+                    next.get_data()
+                ))?;
+                let new_pos = calc_next_pos(*pos, del_pos, forest_rows)?;
+
+                self.map.entry(next.get_data()).and_modify(|e| *e = new_pos);
+            }
+        }
+        Ok(())
+    }
+    fn lookup_targets(&self, targets: &[NodeHash]) -> Vec<u64> {
+        let mut res = Vec::new();
+        for target in targets {
+            res.push(self.map.get(target));
+        }
+        res.into_iter().flatten().copied().collect::<Vec<_>>()
+    }
     /// Adds a single node. Addition is a loop over all new nodes, calling add_single for each
     /// of them
     fn add_single(mut roots: Vec<Node>, node: NodeHash, mut num_leaves: u64) -> Vec<Node> {
@@ -614,7 +673,7 @@ mod test {
         let p = Pollard::new()
             .modify(&hashes, &[])
             .expect("Pollard should not fail");
-        let p = p.modify(&[], &[0]).expect("msg");
+        let p = p.modify(&[], &[hashes[0]]).expect("msg");
 
         let (_, node, _) = p.grab_node(8).unwrap();
         assert_eq!(
@@ -793,7 +852,7 @@ mod test {
         let p = Pollard::new()
             .modify(&hashes, &[])
             .expect("Pollard should not fail")
-            .modify(&[], &[1])
+            .modify(&[], &[hashes[1]])
             .expect("Still should not fail");
 
         assert_eq!(p.roots.len(), 1);
@@ -837,7 +896,10 @@ mod test {
         let dels = case
             .target_values
             .clone()
-            .expect("Del test must have targets");
+            .unwrap()
+            .iter()
+            .map(|pos| hashes[*pos as usize].clone())
+            .collect::<Vec<_>>();
         let p = Pollard::new()
             .modify(&hashes, &[])
             .expect("Test pollards are valid")
@@ -887,8 +949,7 @@ mod test {
         // This is a bug found by fuzzing this lib, where calling detect_offset in an non-existing
         // node would cause a crash. This test makes sure it won't be introduced again
         let elements = get_hash_vec_of(&[0, 2]);
-        let targets = [0_u64];
-        let pollard = Pollard::new().modify(&elements, &targets);
-        assert_eq!(pollard.err().unwrap(), "Node not in forest".to_owned())
+        let pollard = Pollard::new().modify(&elements, &[elements[0]]);
+        assert_eq!(pollard.err().unwrap(), "UTXO 6e340b9cffb37a989ca544e6bb780a2c78901d3fb33738768511a30617afa01d is not in the forest".to_owned())
     }
 }
diff --git a/src/accumulator/proof.rs b/src/accumulator/proof.rs
index a72c299..e474c18 100644
--- a/src/accumulator/proof.rs
+++ b/src/accumulator/proof.rs
@@ -568,7 +568,7 @@ impl Proof {
         Ok((Proof { hashes, targets }, target_hashes))
     }
 
-    fn calc_next_positions(
+    pub(crate) fn calc_next_positions(
         block_targets: &Vec<u64>,
         old_positions: &Vec<(u64, NodeHash)>,
         num_leaves: u64,
diff --git a/src/accumulator/util.rs b/src/accumulator/util.rs
index 5d6956f..bed2d2c 100644
--- a/src/accumulator/util.rs
+++ b/src/accumulator/util.rs
@@ -423,5 +423,8 @@ mod tests {
 
         let res = super::calc_next_pos(1, 9, 3);
         assert_eq!(Ok(9), res);
+
+        let res = super::calc_next_pos(5, 13, tree_rows(8));
+        assert_eq!(Ok(9), res);
     }
 }