diff --git a/barretenberg/ts/src/types/fields.ts b/barretenberg/ts/src/types/fields.ts
index a54cbe5a328..9305f0d6142 100644
--- a/barretenberg/ts/src/types/fields.ts
+++ b/barretenberg/ts/src/types/fields.ts
@@ -2,6 +2,7 @@ import { randomBytes } from '../random/index.js';
 import { toBigIntBE, toBufferBE } from '../bigint-array/index.js';
 import { BufferReader, uint8ArrayToHexString } from '../serialize/index.js';
 
+// TODO(#4189): Replace with implementation in yarn-project/foundation/src/fields/fields.ts
 export class Fr {
   static ZERO = new Fr(0n);
   static MODULUS = 0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001n;
@@ -10,14 +11,14 @@ export class Fr {
   value: Uint8Array;
 
   constructor(value: Uint8Array | bigint) {
-    if (typeof value === 'bigint') {
-      if (value > Fr.MAX_VALUE) {
-        throw new Error(`Fr out of range ${value}.`);
-      }
-      this.value = toBufferBE(value);
-    } else {
-      this.value = value;
+    // We convert buffer value to bigint to be able to check it fits within modulus
+    const valueBigInt = typeof value === 'bigint' ? value : toBigIntBE(value);
+
+    if (valueBigInt > Fr.MAX_VALUE) {
+      throw new Error(`Fr out of range: ${valueBigInt}`);
     }
+
+    this.value = typeof value === 'bigint' ? toBufferBE(value) : value;
   }
 
   static random() {
diff --git a/cspell.json b/cspell.json
index 9180d507c56..b66546c31b1 100644
--- a/cspell.json
+++ b/cspell.json
@@ -79,7 +79,7 @@
     "erc",
     "falsey",
     "fargate",
-    "Fieldeable",
+    "Fieldable",
     "filestat",
     "finalise",
     "finalised",
diff --git a/noir-projects/aztec-nr/aztec/src/note/utils.nr b/noir-projects/aztec-nr/aztec/src/note/utils.nr
index 8732ca6be61..49311d794af 100644
--- a/noir-projects/aztec-nr/aztec/src/note/utils.nr
+++ b/noir-projects/aztec-nr/aztec/src/note/utils.nr
@@ -71,8 +71,8 @@ pub fn compute_note_hash_for_consumption<Note, N>(note: Note) -> Field where Not
     } else {
         // When nonce is nonzero, that means we are reading a settled note (from tree) created in a
         // previous TX. So we need the unique_siloed_note_hash which has already been hashed with
-        // contract address and then nonce. This hash will match the existing leaf in the private
-        // data tree, so the kernel can just perform a membership check directly on this hash/leaf.
+        // contract address and then nonce. This hash will match the existing leaf in the note hash
+        // tree, so the kernel can just perform a membership check directly on this hash/leaf.
         compute_unique_siloed_note_hash(note)
         // IMPORTANT NOTE ON REDUNDANT SILOING BY CONTRACT ADDRESS: The note hash computed above is
         // "siloed" by contract address. When a note hash is computed solely for the purpose of
@@ -81,7 +81,7 @@ pub fn compute_note_hash_for_consumption<Note, N>(note: Note) -> Field where Not
         // be computed from a siloed note hash. After all, persistable note hashes and nullifiers are
         // siloed by the kernel circuit. That being said, the siloed note hash computed above CAN be
         // used for nullifier computation, and this achieves the (arguably unnecessary) property that
-        // nullifiers are computed from a note hash's fully-computed private data tree leaf.
+        // nullifiers are computed from a note hash's fully-computed note hash tree leaf.
     }
 }
 
diff --git a/yarn-project/circuits.js/src/contract/private_function.ts b/yarn-project/circuits.js/src/contract/private_function.ts
index ea244b9d94a..b0395155e1c 100644
--- a/yarn-project/circuits.js/src/contract/private_function.ts
+++ b/yarn-project/circuits.js/src/contract/private_function.ts
@@ -32,7 +32,7 @@ export function computePrivateFunctionLeaf(fn: PrivateFunction): Buffer {
 
 function getPrivateFunctionTreeCalculator(): MerkleTreeCalculator {
   if (!privateFunctionTreeCalculator) {
-    const functionTreeZeroLeaf = pedersenHash(new Array(PRIVATE_FUNCTION_SIZE).fill(Buffer.alloc(32))).toBuffer();
+    const functionTreeZeroLeaf = pedersenHash(new Array(PRIVATE_FUNCTION_SIZE).fill(0)).toBuffer();
     privateFunctionTreeCalculator = new MerkleTreeCalculator(FUNCTION_TREE_HEIGHT, functionTreeZeroLeaf);
   }
   return privateFunctionTreeCalculator;
diff --git a/yarn-project/circuits.js/src/hash/hash.ts b/yarn-project/circuits.js/src/hash/hash.ts
index b5f4f1c0a63..b5496f75713 100644
--- a/yarn-project/circuits.js/src/hash/hash.ts
+++ b/yarn-project/circuits.js/src/hash/hash.ts
@@ -61,7 +61,7 @@ export function hashVK(vkBuf: Buffer) {
  * @returns A commitment nonce.
  */
 export function computeCommitmentNonce(nullifierZero: Fr, commitmentIndex: number): Fr {
-  return pedersenHash([nullifierZero, numToUInt32BE(commitmentIndex, 32)], GeneratorIndex.NOTE_HASH_NONCE);
+  return pedersenHash([nullifierZero, commitmentIndex], GeneratorIndex.NOTE_HASH_NONCE);
 }
 
 /**
diff --git a/yarn-project/foundation/src/crypto/pedersen/pedersen.wasm.ts b/yarn-project/foundation/src/crypto/pedersen/pedersen.wasm.ts
index 29fc82dcac3..bb07994bb95 100644
--- a/yarn-project/foundation/src/crypto/pedersen/pedersen.wasm.ts
+++ b/yarn-project/foundation/src/crypto/pedersen/pedersen.wasm.ts
@@ -1,7 +1,7 @@
 import { BarretenbergSync, Fr as FrBarretenberg } from '@aztec/bb.js';
 
 import { Fr } from '../../fields/fields.js';
-import { type Bufferable, serializeToBufferArray } from '../../serialize/serialize.js';
+import { type Fieldable, serializeToFields } from '../../serialize/serialize.js';
 
 /**
  * Create a pedersen commitment (point) from an array of input fields.
@@ -20,19 +20,17 @@ export function pedersenCommit(input: Buffer[]) {
 
 /**
  * Create a pedersen hash (field) from an array of input fields.
- * Left pads any inputs less than 32 bytes.
+ * @param input - The input fieldables to hash.
+ * @param index - The separator index to use for the hash.
+ * @returns The pedersen hash.
  */
-export function pedersenHash(input: Bufferable[], index = 0): Fr {
-  let bufferredInput = serializeToBufferArray(input);
-  if (!bufferredInput.every(i => i.length <= 32)) {
-    throw new Error('All Pedersen Hash input buffers must be <= 32 bytes.');
-  }
-  bufferredInput = bufferredInput.map(i => (i.length < 32 ? Buffer.concat([Buffer.alloc(32 - i.length, 0), i]) : i));
+export function pedersenHash(input: Fieldable[], index = 0): Fr {
+  const inputFields = serializeToFields(input);
   return Fr.fromBuffer(
     Buffer.from(
       BarretenbergSync.getSingleton()
         .pedersenHash(
-          bufferredInput.map(i => new FrBarretenberg(i)),
+          inputFields.map(i => new FrBarretenberg(i.toBuffer())), // TODO(#4189): remove this stupid conversion
           index,
         )
         .toBuffer(),
diff --git a/yarn-project/foundation/src/crypto/poseidon/index.ts b/yarn-project/foundation/src/crypto/poseidon/index.ts
index 8f77b580211..b02b09e16ed 100644
--- a/yarn-project/foundation/src/crypto/poseidon/index.ts
+++ b/yarn-project/foundation/src/crypto/poseidon/index.ts
@@ -1,16 +1,24 @@
 import { BarretenbergSync, Fr as FrBarretenberg } from '@aztec/bb.js';
 
 import { Fr } from '../../fields/fields.js';
+import { type Fieldable, serializeToFields } from '../../serialize/serialize.js';
 
 /**
  * Create a poseidon hash (field) from an array of input fields.
- * Left pads any inputs less than 32 bytes.
+ * @param input - The input fields to hash.
+ * @param index - The separator index to use for the hash.
+ * @returns The poseidon hash.
+ * TODO(#5714): enable index once barretenberg API supports it
  */
-export function poseidonHash(input: Buffer[]): Fr {
+export function poseidonHash(input: Fieldable[], _index = 0): Fr {
+  const inputFields = serializeToFields(input);
   return Fr.fromBuffer(
     Buffer.from(
       BarretenbergSync.getSingleton()
-        .poseidonHash(input.map(i => new FrBarretenberg(i)))
+        .poseidonHash(
+          inputFields.map(i => new FrBarretenberg(i.toBuffer())), // TODO(#4189): remove this stupid conversion
+          // index, // TODO: enable once the barretenberg API supports it
+        )
         .toBuffer(),
     ),
   );
diff --git a/yarn-project/foundation/src/serialize/serialize.ts b/yarn-project/foundation/src/serialize/serialize.ts
index c610b5fea64..eaa81c27c7f 100644
--- a/yarn-project/foundation/src/serialize/serialize.ts
+++ b/yarn-project/foundation/src/serialize/serialize.ts
@@ -121,11 +121,19 @@ export type Bufferable =
   | Bufferable[];
 
 /** A type that can be converted to a Field or a Field array. */
-export type Fieldeable =
+export type Fieldable =
   | Fr
   | boolean
   | number
   | bigint
+  | Buffer
+  | {
+      /**
+       * Serialize to a field.
+       * @dev Duplicate to `toField` but left as is as it is used in AVM codebase.
+       */
+      toFr: () => Fr;
+    }
   | {
       /** Serialize to a field. */
       toField: () => Fr;
@@ -134,7 +142,7 @@ export type Fieldeable =
       /** Serialize to an array of fields. */
       toFields: () => Fr[];
     }
-  | Fieldeable[];
+  | Fieldable[];
 
 /**
  * Serializes a list of objects contiguously.
@@ -142,10 +150,10 @@ export type Fieldeable =
  * @returns A buffer list with the concatenation of all fields.
  */
 export function serializeToBufferArray(...objs: Bufferable[]): Buffer[] {
-  let ret: Buffer[] = [];
+  const ret: Buffer[] = [];
   for (const obj of objs) {
     if (Array.isArray(obj)) {
-      ret = [...ret, ...serializeToBufferArray(...obj)];
+      ret.push(...serializeToBufferArray(...obj));
     } else if (Buffer.isBuffer(obj)) {
       ret.push(obj);
     } else if (typeof obj === 'boolean') {
@@ -176,19 +184,25 @@ export function serializeToBufferArray(...objs: Bufferable[]): Buffer[] {
  * @param objs - Objects to serialize.
  * @returns An array of fields with the concatenation of all fields.
  */
-export function serializeToFields(...objs: Fieldeable[]): Fr[] {
-  let ret: Fr[] = [];
+export function serializeToFields(...objs: Fieldable[]): Fr[] {
+  const ret: Fr[] = [];
   for (const obj of objs) {
     if (Array.isArray(obj)) {
-      ret = [...ret, ...serializeToFields(...obj)];
+      ret.push(...serializeToFields(...obj));
     } else if (obj instanceof Fr) {
       ret.push(obj);
     } else if (typeof obj === 'boolean' || typeof obj === 'number' || typeof obj === 'bigint') {
       ret.push(new Fr(obj));
     } else if ('toFields' in obj) {
-      ret = [...ret, ...obj.toFields()];
-    } else {
+      ret.push(...obj.toFields());
+    } else if ('toFr' in obj) {
+      ret.push(obj.toFr());
+    } else if ('toField' in obj) {
       ret.push(obj.toField());
+    } else if (Buffer.isBuffer(obj)) {
+      ret.push(Fr.fromBuffer(obj));
+    } else {
+      throw new Error(`Cannot serialize input to field: ${typeof obj} ${(obj as any).constructor?.name}`);
     }
   }
   return ret;
diff --git a/yarn-project/merkle-tree/src/pedersen.ts b/yarn-project/merkle-tree/src/pedersen.ts
index b49c34c527e..8ddfa636549 100644
--- a/yarn-project/merkle-tree/src/pedersen.ts
+++ b/yarn-project/merkle-tree/src/pedersen.ts
@@ -1,4 +1,5 @@
 import { pedersenHash } from '@aztec/foundation/crypto';
+import { Fr } from '@aztec/foundation/fields';
 import { type Hasher } from '@aztec/types/interfaces';
 
 /**
@@ -12,7 +13,7 @@ export class Pedersen implements Hasher {
    * purposes.
    */
   public hash(lhs: Uint8Array, rhs: Uint8Array): Buffer {
-    return pedersenHash([Buffer.from(lhs), Buffer.from(rhs)]).toBuffer();
+    return pedersenHash([Fr.fromBuffer(Buffer.from(lhs)), Fr.fromBuffer(Buffer.from(rhs))]).toBuffer();
   }
 
   /*
@@ -20,6 +21,7 @@ export class Pedersen implements Hasher {
    * purposes.
    */
   public hashInputs(inputs: Buffer[]): Buffer {
-    return pedersenHash(inputs).toBuffer();
+    const inputFields = inputs.map(i => Fr.fromBuffer(i));
+    return pedersenHash(inputFields).toBuffer();
   }
 }
diff --git a/yarn-project/merkle-tree/src/snapshots/append_only_snapshot.test.ts b/yarn-project/merkle-tree/src/snapshots/append_only_snapshot.test.ts
index 111f6de0439..e68bde0ee71 100644
--- a/yarn-project/merkle-tree/src/snapshots/append_only_snapshot.test.ts
+++ b/yarn-project/merkle-tree/src/snapshots/append_only_snapshot.test.ts
@@ -1,4 +1,4 @@
-import { randomBytes } from '@aztec/foundation/crypto';
+import { Fr } from '@aztec/foundation/fields';
 import { type FromBuffer } from '@aztec/foundation/serialize';
 import { type AztecKVStore } from '@aztec/kv-store';
 import { openTmpStore } from '@aztec/kv-store/utils';
@@ -24,7 +24,7 @@ describe('AppendOnlySnapshot', () => {
     () => tree,
     () => snapshotBuilder,
     async tree => {
-      const newLeaves = Array.from({ length: 2 }).map(() => randomBytes(32));
+      const newLeaves = Array.from({ length: 2 }).map(() => Fr.random().toBuffer());
       await tree.appendLeaves(newLeaves);
     },
   );
diff --git a/yarn-project/merkle-tree/src/snapshots/full_snapshot.test.ts b/yarn-project/merkle-tree/src/snapshots/full_snapshot.test.ts
index 486f633262a..be8a8572f6c 100644
--- a/yarn-project/merkle-tree/src/snapshots/full_snapshot.test.ts
+++ b/yarn-project/merkle-tree/src/snapshots/full_snapshot.test.ts
@@ -1,4 +1,4 @@
-import { randomBytes } from '@aztec/foundation/crypto';
+import { Fr } from '@aztec/foundation/fields';
 import { type FromBuffer } from '@aztec/foundation/serialize';
 import { type AztecKVStore } from '@aztec/kv-store';
 import { openTmpStore } from '@aztec/kv-store/utils';
@@ -23,7 +23,7 @@ describe('FullSnapshotBuilder', () => {
     () => tree,
     () => snapshotBuilder,
     async () => {
-      const newLeaves = Array.from({ length: 2 }).map(() => randomBytes(32));
+      const newLeaves = Array.from({ length: 2 }).map(() => Fr.random().toBuffer());
       await tree.appendLeaves(newLeaves);
     },
   );
diff --git a/yarn-project/merkle-tree/src/sparse_tree/sparse_tree.test.ts b/yarn-project/merkle-tree/src/sparse_tree/sparse_tree.test.ts
index e949192e900..56cbaee0a58 100644
--- a/yarn-project/merkle-tree/src/sparse_tree/sparse_tree.test.ts
+++ b/yarn-project/merkle-tree/src/sparse_tree/sparse_tree.test.ts
@@ -1,5 +1,6 @@
 import { SiblingPath } from '@aztec/circuit-types';
-import { randomBigInt, randomBytes } from '@aztec/foundation/crypto';
+import { randomBigInt } from '@aztec/foundation/crypto';
+import { Fr } from '@aztec/foundation/fields';
 import { createDebugLogger } from '@aztec/foundation/log';
 import { type AztecKVStore } from '@aztec/kv-store';
 import { openTmpStore } from '@aztec/kv-store/utils';
@@ -71,11 +72,11 @@ describe('SparseTreeSpecific', () => {
     expect(tree.getNumLeaves(false)).toEqual(0n);
 
     // Insert a leaf
-    await tree.updateLeaf(randomBytes(32), randomIndex);
+    await tree.updateLeaf(Fr.random().toBuffer(), randomIndex);
     expect(tree.getNumLeaves(true)).toEqual(1n);
 
     // Update a leaf
-    await tree.updateLeaf(randomBytes(32), randomIndex);
+    await tree.updateLeaf(Fr.random().toBuffer(), randomIndex);
     expect(tree.getNumLeaves(true)).toEqual(1n);
   });
 
@@ -90,7 +91,7 @@ describe('SparseTreeSpecific', () => {
     expect(tree.getNumLeaves(false)).toEqual(0n);
 
     // Insert a leaf
-    await tree.updateLeaf(randomBytes(32), randomIndex);
+    await tree.updateLeaf(Fr.random().toBuffer(), randomIndex);
     expect(tree.getNumLeaves(true)).toEqual(1n);
 
     // Delete a leaf
@@ -110,7 +111,7 @@ describe('SparseTreeSpecific', () => {
 
     // Insert leaf at index 3
     let level1LeftHash: Buffer;
-    const leafAtIndex3 = randomBytes(32);
+    const leafAtIndex3 = Fr.random().toBuffer();
     {
       await tree.updateLeaf(leafAtIndex3, 3n);
       expect(tree.getNumLeaves(true)).toEqual(1n);
@@ -126,7 +127,7 @@ describe('SparseTreeSpecific', () => {
     // Insert leaf at index 6
     let level1RightHash: Buffer;
     {
-      const leafAtIndex6 = randomBytes(32);
+      const leafAtIndex6 = Fr.random().toBuffer();
       await tree.updateLeaf(leafAtIndex6, 6n);
       expect(tree.getNumLeaves(true)).toEqual(2n);
       const level2Hash = pedersen.hash(leafAtIndex6, INITIAL_LEAF);
@@ -139,7 +140,7 @@ describe('SparseTreeSpecific', () => {
     }
 
     // Insert leaf at index 2
-    const leafAtIndex2 = randomBytes(32);
+    const leafAtIndex2 = Fr.random().toBuffer();
     {
       await tree.updateLeaf(leafAtIndex2, 2n);
       expect(tree.getNumLeaves(true)).toEqual(3n);
@@ -154,7 +155,7 @@ describe('SparseTreeSpecific', () => {
 
     // Updating leaf at index 3
     {
-      const updatedLeafAtIndex3 = randomBytes(32);
+      const updatedLeafAtIndex3 = Fr.random().toBuffer();
       await tree.updateLeaf(updatedLeafAtIndex3, 3n);
       expect(tree.getNumLeaves(true)).toEqual(3n);
       const level2Hash = pedersen.hash(leafAtIndex2, updatedLeafAtIndex3);
@@ -175,7 +176,7 @@ describe('SparseTreeSpecific', () => {
     const db = openTmpStore();
     const tree = await createDb(db, pedersen, 'test', depth);
 
-    const leaves = Array.from({ length: 1000 }).map(() => randomBytes(32));
+    const leaves = Array.from({ length: 1000 }).map(() => Fr.random().toBuffer());
     const indices = Array.from({ length: 1000 }).map(() => randomBigInt(BigInt(maxIndex)));
 
     const start = Date.now();
diff --git a/yarn-project/merkle-tree/src/standard_tree/standard_tree.test.ts b/yarn-project/merkle-tree/src/standard_tree/standard_tree.test.ts
index cd946ac771a..b01409eb14c 100644
--- a/yarn-project/merkle-tree/src/standard_tree/standard_tree.test.ts
+++ b/yarn-project/merkle-tree/src/standard_tree/standard_tree.test.ts
@@ -1,4 +1,4 @@
-import { randomBytes } from '@aztec/foundation/crypto';
+import { Fr } from '@aztec/foundation/fields';
 import { type FromBuffer } from '@aztec/foundation/serialize';
 import { type AztecKVStore } from '@aztec/kv-store';
 import { openTmpStore } from '@aztec/kv-store/utils';
@@ -41,7 +41,7 @@ describe('StandardTree_batchAppend', () => {
   it('correctly computes root when batch appending and calls hash function expected num times', async () => {
     const db = openTmpStore();
     const tree = await createDb(db, pedersen, 'test', 3);
-    const leaves = Array.from({ length: 5 }, _ => randomBytes(32));
+    const leaves = Array.from({ length: 5 }, _ => Fr.random().toBuffer());
 
     pedersen.resetCounter();
     await tree.appendLeaves(leaves);
diff --git a/yarn-project/merkle-tree/src/test/standard_based_test_suite.ts b/yarn-project/merkle-tree/src/test/standard_based_test_suite.ts
index a2533ad9e6d..6f8fc6d0987 100644
--- a/yarn-project/merkle-tree/src/test/standard_based_test_suite.ts
+++ b/yarn-project/merkle-tree/src/test/standard_based_test_suite.ts
@@ -1,5 +1,5 @@
 import { SiblingPath } from '@aztec/circuit-types';
-import { randomBytes } from '@aztec/foundation/crypto';
+import { Fr } from '@aztec/foundation/fields';
 import { type AztecKVStore } from '@aztec/kv-store';
 import { openTmpStore } from '@aztec/kv-store/utils';
 import { type Hasher } from '@aztec/types/interfaces';
@@ -44,7 +44,7 @@ export const standardBasedTreeTestSuite = (
     it('should throw when appending beyond max index', async () => {
       const db = openTmpStore();
       const tree = await createDb(db, pedersen, 'test', 2);
-      const leaves = Array.from({ length: 5 }, _ => randomBytes(32));
+      const leaves = Array.from({ length: 5 }, _ => Fr.random().toBuffer());
       await expect(appendLeaves(tree, leaves)).rejects.toThrow();
     });
 
diff --git a/yarn-project/simulator/src/avm/avm_simulator.test.ts b/yarn-project/simulator/src/avm/avm_simulator.test.ts
index 78d0aa01011..3e932af1294 100644
--- a/yarn-project/simulator/src/avm/avm_simulator.test.ts
+++ b/yarn-project/simulator/src/avm/avm_simulator.test.ts
@@ -5,6 +5,7 @@ import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { keccak, pedersenHash, poseidonHash, sha256 } from '@aztec/foundation/crypto';
 import { EthAddress } from '@aztec/foundation/eth-address';
 import { Fr } from '@aztec/foundation/fields';
+import { type Fieldable } from '@aztec/foundation/serialize';
 import { AvmNestedCallsTestContractArtifact, AvmTestContractArtifact } from '@aztec/noir-contracts.js';
 
 import { jest } from '@jest/globals';
@@ -140,11 +141,11 @@ describe('AVM simulator: transpiled Noir contracts', () => {
   describe.each([
     ['poseidon_hash', poseidonHash],
     ['pedersen_hash', pedersenHash],
-    ['pedersen_hash_with_index', (m: Buffer[]) => pedersenHash(m, 20)],
-  ])('Hashes with field returned in noir contracts', (name: string, hashFunction: (data: Buffer[]) => Fr) => {
+    ['pedersen_hash_with_index', (m: Fieldable[]) => pedersenHash(m, 20)],
+  ])('Hashes with field returned in noir contracts', (name: string, hashFunction: (data: Fieldable[]) => Fr) => {
     it(`Should execute contract function that performs ${name} hash`, async () => {
       const calldata = [new Fr(1), new Fr(2), new Fr(3)];
-      const hash = hashFunction(calldata.map(f => f.toBuffer()));
+      const hash = hashFunction(calldata);
 
       const context = initContext({ env: initExecutionEnvironment({ calldata }) });
       const bytecode = getAvmTestContractBytecode(name);
diff --git a/yarn-project/simulator/src/avm/opcodes/hashing.test.ts b/yarn-project/simulator/src/avm/opcodes/hashing.test.ts
index 42e6d690e48..3986bd73b2b 100644
--- a/yarn-project/simulator/src/avm/opcodes/hashing.test.ts
+++ b/yarn-project/simulator/src/avm/opcodes/hashing.test.ts
@@ -41,7 +41,7 @@ describe('Hashing Opcodes', () => {
 
       const dstOffset = 3;
 
-      const expectedHash = poseidonHash(args.map(field => field.toBuffer()));
+      const expectedHash = poseidonHash(args);
       await new Poseidon2(indirect, dstOffset, messageOffset, args.length).execute(context);
 
       const result = context.machineState.memory.get(dstOffset);
@@ -62,7 +62,7 @@ describe('Hashing Opcodes', () => {
 
       const dstOffset = 3;
 
-      const expectedHash = poseidonHash(args.map(field => field.toBuffer()));
+      const expectedHash = poseidonHash(args);
       await new Poseidon2(indirect, dstOffset, messageOffset, args.length).execute(context);
 
       const result = context.machineState.memory.get(dstOffset);
diff --git a/yarn-project/simulator/src/avm/opcodes/hashing.ts b/yarn-project/simulator/src/avm/opcodes/hashing.ts
index 31c5f7ac54c..500bbf46cbd 100644
--- a/yarn-project/simulator/src/avm/opcodes/hashing.ts
+++ b/yarn-project/simulator/src/avm/opcodes/hashing.ts
@@ -41,7 +41,7 @@ export class Poseidon2 extends Instruction {
     );
 
     // Memory pointer will be indirect
-    const hashData = memory.getSlice(messageOffset, this.messageSize).map(word => word.toBuffer());
+    const hashData = memory.getSlice(messageOffset, this.messageSize);
 
     const hash = poseidonHash(hashData);
     memory.set(dstOffset, new Field(hash));