diff --git a/yarn-project/circuits.js/src/merkle/merkle_tree_calculator.ts b/yarn-project/circuits.js/src/merkle/merkle_tree_calculator.ts
index 471c0f776bd..c8d4870039c 100644
--- a/yarn-project/circuits.js/src/merkle/merkle_tree_calculator.ts
+++ b/yarn-project/circuits.js/src/merkle/merkle_tree_calculator.ts
@@ -1,5 +1,4 @@
 import { pedersenHash } from '@aztec/foundation/crypto';
-import { Fr } from '@aztec/foundation/fields';
 
 import { MerkleTree } from './merkle_tree.js';
 
@@ -13,7 +12,7 @@ export class MerkleTreeCalculator {
   constructor(
     private height: number,
     zeroLeaf = Buffer.alloc(32),
-    hasher = (left: Buffer, right: Buffer) => pedersenHash([Fr.fromBuffer(left), Fr.fromBuffer(right)]).toBuffer(),
+    hasher = (left: Buffer, right: Buffer) => pedersenHash([left, right]).toBuffer(),
   ) {
     this.hasher = hasher;
     this.zeroHashes = Array.from({ length: height }).reduce(
diff --git a/yarn-project/circuits.js/src/merkle/sibling_path.ts b/yarn-project/circuits.js/src/merkle/sibling_path.ts
index 4a31d3a7a23..52383dae87c 100644
--- a/yarn-project/circuits.js/src/merkle/sibling_path.ts
+++ b/yarn-project/circuits.js/src/merkle/sibling_path.ts
@@ -1,12 +1,11 @@
 import { pedersenHash } from '@aztec/foundation/crypto';
-import { Fr } from '@aztec/foundation/fields';
 
 /** Computes the expected root of a merkle tree given a leaf and its sibling path. */
 export function computeRootFromSiblingPath(
   leaf: Buffer,
   siblingPath: Buffer[],
   index: number,
-  hasher = (left: Buffer, right: Buffer) => pedersenHash([Fr.fromBuffer(left), Fr.fromBuffer(right)]).toBuffer(),
+  hasher = (left: Buffer, right: Buffer) => pedersenHash([left, right]).toBuffer(),
 ) {
   let result = leaf;
   for (const sibling of siblingPath) {
diff --git a/yarn-project/foundation/src/crypto/pedersen/index.test.ts b/yarn-project/foundation/src/crypto/pedersen/index.test.ts
index 5b2f1b435a2..0e9e1c1c92a 100644
--- a/yarn-project/foundation/src/crypto/pedersen/index.test.ts
+++ b/yarn-project/foundation/src/crypto/pedersen/index.test.ts
@@ -27,12 +27,12 @@ describe('pedersen', () => {
   });
 
   it('pedersen hash', () => {
-    const r = pedersenHash([1n, 1n]);
+    const r = pedersenHash([toBufferBE(1n, 32), toBufferBE(1n, 32)]);
     expect(r.toString()).toEqual('0x07ebfbf4df29888c6cd6dca13d4bb9d1a923013ddbbcbdc3378ab8845463297b');
   });
 
   it('pedersen hash with index', () => {
-    const r = pedersenHash([1n, 1n], 5);
+    const r = pedersenHash([toBufferBE(1n, 32), toBufferBE(1n, 32)], 5);
     expect(r.toString()).toEqual('0x1c446df60816b897cda124524e6b03f36df0cec333fad87617aab70d7861daa6');
   });