diff --git a/evm/Cargo.toml b/evm/Cargo.toml
index 7c179318..1327635d 100644
--- a/evm/Cargo.toml
+++ b/evm/Cargo.toml
@@ -7,7 +7,7 @@ edition = "2021"
 [dependencies]
 plonky2 = { path = "../plonky2", default-features = false, features = ["rand", "timing"] }
 plonky2_util = { path = "../util" }
-eth_trie_utils = "0.2.1"
+eth_trie_utils = "0.3.1"
 anyhow = "1.0.40"
 env_logger = "0.9.0"
 ethereum-types = "0.14.0"
diff --git a/evm/src/cpu/kernel/tests/mpt/insert.rs b/evm/src/cpu/kernel/tests/mpt/insert.rs
index 35ab6e80..c92a7e62 100644
--- a/evm/src/cpu/kernel/tests/mpt/insert.rs
+++ b/evm/src/cpu/kernel/tests/mpt/insert.rs
@@ -142,7 +142,7 @@ fn mpt_insert_branch_to_leaf_same_key() -> Result<()> {
 
 /// Note: The account's storage_root is ignored, as we can't insert a new storage_root without the
 /// accompanying trie data. An empty trie's storage_root is used instead.
-fn test_state_trie(state_trie: PartialTrie, k: Nibbles, mut account: AccountRlp) -> Result<()> {
+fn test_state_trie(mut state_trie: PartialTrie, k: Nibbles, mut account: AccountRlp) -> Result<()> {
     assert_eq!(k.count, 64);
 
     // Ignore any storage_root; see documentation note.
@@ -207,8 +207,8 @@ fn test_state_trie(state_trie: PartialTrie, k: Nibbles, mut account: AccountRlp)
     );
     let hash = H256::from_uint(&interpreter.stack()[0]);
 
-    let updated_trie = state_trie.insert(k, rlp::encode(&account).to_vec());
-    let expected_state_trie_hash = updated_trie.calc_hash();
+    state_trie.insert(k, rlp::encode(&account).to_vec());
+    let expected_state_trie_hash = state_trie.calc_hash();
     assert_eq!(hash, expected_state_trie_hash);
 
     Ok(())
diff --git a/evm/src/generation/mpt.rs b/evm/src/generation/mpt.rs
index 4107b978..a5be1205 100644
--- a/evm/src/generation/mpt.rs
+++ b/evm/src/generation/mpt.rs
@@ -109,7 +109,7 @@ pub(crate) fn mpt_prover_inputs_state_trie(
             prover_inputs.push(U256::zero()); // value_present = 0
 
             for (i, child) in children.iter().enumerate() {
-                let extended_key = key.merge(&Nibbles {
+                let extended_key = key.merge_nibbles(&Nibbles {
                     count: 1,
                     packed: i.into(),
                 });
@@ -124,7 +124,7 @@ pub(crate) fn mpt_prover_inputs_state_trie(
         PartialTrie::Extension { nibbles, child } => {
             prover_inputs.push(nibbles.count.into());
             prover_inputs.push(nibbles.packed);
-            let extended_key = key.merge(nibbles);
+            let extended_key = key.merge_nibbles(nibbles);
             mpt_prover_inputs_state_trie(
                 child,
                 extended_key,