diff --git a/src/merkle/smt/mod.rs b/src/merkle/smt/mod.rs
index becb3f2..255f6ba 100644
--- a/src/merkle/smt/mod.rs
+++ b/src/merkle/smt/mod.rs
@@ -350,10 +350,11 @@ pub(crate) trait SparseMerkleTree<const DEPTH: u8> {
     /// The length `path` is guaranteed to be equal to `DEPTH`
     fn path_and_leaf_to_opening(path: MerklePath, leaf: Self::Leaf) -> Self::Opening;
 
+    #[cfg_attr(not(test), allow(dead_code))]
     fn sorted_pairs_to_leaves(
         pairs: Vec<(Self::Key, Self::Value)>,
-    ) -> PrecomputedSubtrees<Self::Leaf> {
-        let mut accumulator: PrecomputedSubtrees<Self::Leaf> = Default::default();
+    ) -> PrecomputedSubtrees<u64, Self::Leaf> {
+        let mut accumulator: PrecomputedSubtrees<u64, Self::Leaf> = Default::default();
 
         // The kv-pairs we've seen so far that correspond to a single leaf.
         let mut current_leaf_buffer: Vec<(Self::Key, Self::Value)> = Default::default();
@@ -632,14 +633,14 @@ impl SubtreeLeaf {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct PrecomputedSubtrees<L> {
+pub struct PrecomputedSubtrees<K, L> {
     /// Literal leaves to be added to the sparse Merkle tree's internal mapping.
-    pub nodes: BTreeMap<u64, L>,
+    pub nodes: BTreeMap<K, L>,
     /// "Conceptual" leaves that will be used for computations.
     pub leaves: Vec<Vec<SubtreeLeaf>>,
 }
 
-impl<L> PrecomputedSubtrees<L> {
+impl<K, L> PrecomputedSubtrees<K, L> {
     pub fn add_leaf(&mut self, leaf: SubtreeLeaf) {
         let last_subtree = match self.leaves.last_mut() {
             // Base case.
@@ -670,7 +671,7 @@ impl<L> PrecomputedSubtrees<L> {
 }
 
 // Derive requires `L` to impl Default, even though we don't actually need that.
-impl<L> Default for PrecomputedSubtrees<L> {
+impl<K, L> Default for PrecomputedSubtrees<K, L> {
     fn default() -> Self {
         Self {
             nodes: Default::default(),