diff --git a/Cargo.toml b/Cargo.toml
index 9ee988c..4dd12fc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "nmt-rs"
-version = "0.2.1"
+version = "0.2.3"
 edition = "2021"
 description = "A namespaced merkle tree compatible with Celestia"
 license = "MIT OR Apache-2.0"
@@ -21,7 +21,7 @@ nmt-rs = { path = ".", features = ["borsh", "serde"] }
 borsh = { version = "1" }
 serde_json = "1.0.96"
 postcard = { version = "1.0.4", features = ["use-std"] }
-tendermint = { version = "0.35.0" }
+tendermint = { version = "0.39.1" }
 
 [features]
 default = ["std"]
diff --git a/README.md b/README.md
index d436d15..fd718f8 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ This code has not been audited, and may contain critical vulnerabilities. Do not
 
 - [x] Verify namespace range proofs
 
+- [x] Narrow namespace range proofs: supply part of the range to generate a proof for the remaining sub-range
 
 ## License
 
diff --git a/src/nmt_proof.rs b/src/nmt_proof.rs
index 600a99a..f46fc57 100644
--- a/src/nmt_proof.rs
+++ b/src/nmt_proof.rs
@@ -3,7 +3,6 @@
 //! - A range of leaves forms a complete namespace
 //! - A range of leaves all exists in the same namespace
 use crate::maybestd::{mem, vec::Vec};
-use crate::simple_merkle::db::MemDb;
 use crate::{
     namespaced_hash::{NamespaceId, NamespaceMerkleHasher, NamespacedHash},
     simple_merkle::{
@@ -118,23 +117,18 @@ where
             return Err(RangeProofError::WrongAmountOfLeavesProvided);
         }
 
-        // TODO: make this more concise
-        let left_extra_hashes: Vec<_> = left_extra_raw_leaves
-            .iter()
-            .map(|data| {
-                M::with_ignore_max_ns(self.ignores_max_ns())
-                    .hash_leaf_with_namespace(data.as_ref(), leaf_namespace)
-            })
-            .collect();
-        let right_extra_hashes: Vec<_> = right_extra_raw_leaves
-            .iter()
-            .map(|data| {
-                M::with_ignore_max_ns(self.ignores_max_ns())
-                    .hash_leaf_with_namespace(data.as_ref(), leaf_namespace)
-            })
-            .collect();
+        let leaves_to_hashes = |l: &[L]| -> Vec<NamespacedHash<NS_ID_SIZE>> {
+            l.iter()
+                .map(|data| {
+                    M::with_ignore_max_ns(self.ignores_max_ns())
+                        .hash_leaf_with_namespace(data.as_ref(), leaf_namespace)
+                })
+                .collect()
+        };
+        let left_extra_hashes = leaves_to_hashes(left_extra_raw_leaves);
+        let right_extra_hashes = leaves_to_hashes(right_extra_raw_leaves);
 
-        let mut tree = NamespaceMerkleTree::<MemDb<M::Output>, M, NS_ID_SIZE>::with_hasher(
+        let mut tree = NamespaceMerkleTree::<NoopDb, M, NS_ID_SIZE>::with_hasher(
             M::with_ignore_max_ns(self.ignores_max_ns()),
         );
 
diff --git a/src/simple_merkle/proof.rs b/src/simple_merkle/proof.rs
index d39ed13..6e8a232 100644
--- a/src/simple_merkle/proof.rs
+++ b/src/simple_merkle/proof.rs
@@ -1,7 +1,7 @@
 use core::ops::Range;
 
 use super::{
-    db::{MemDb, NoopDb},
+    db::NoopDb,
     error::RangeProofError,
     tree::{MerkleHash, MerkleTree},
     utils::compute_num_left_siblings,
@@ -100,9 +100,12 @@ where
         let new_start_idx = (self.start_idx() as usize)
             .checked_add(left_extra_leaves.len())
             .ok_or(RangeProofError::TreeTooLarge)?;
-        let new_end_idx = new_start_idx + self.range_len() - new_leaf_len as usize; // TODO safe arithmetic
+        let new_end_idx = new_start_idx
+            .checked_add(self.range_len())
+            .and_then(|i| i.checked_sub(new_leaf_len))
+            .ok_or(RangeProofError::TreeTooLarge)?;
 
-        let mut tree = MerkleTree::<MemDb<M::Output>, M>::with_hasher(hasher);
+        let mut tree = MerkleTree::<NoopDb, M>::with_hasher(hasher);
         tree.narrow_range_proof(
             left_extra_leaves,
             new_start_idx..new_end_idx,