diff --git a/docs/classes/_src_base_.base.md b/docs/classes/_src_base_.base.md
index d3c6a5c..dee8c3f 100644
--- a/docs/classes/_src_base_.base.md
+++ b/docs/classes/_src_base_.base.md
@@ -18,15 +18,18 @@
 * [_isHexString](_src_base_.base.md#protected-_ishexstring)
 * [_log2](_src_base_.base.md#protected-_log2)
 * [_zip](_src_base_.base.md#protected-_zip)
+* [bigNumberify](_src_base_.base.md#bignumberify)
 * [binarySearch](_src_base_.base.md#binarysearch)
 * [bufferToHex](_src_base_.base.md#buffertohex)
 * [bufferify](_src_base_.base.md#bufferify)
 * [bufferifyFn](_src_base_.base.md#bufferifyfn)
 * [linearSearch](_src_base_.base.md#linearsearch)
 * [print](_src_base_.base.md#print)
+* [bigNumberify](_src_base_.base.md#static-bignumberify)
 * [binarySearch](_src_base_.base.md#static-binarysearch)
 * [bufferToHex](_src_base_.base.md#static-buffertohex)
 * [bufferify](_src_base_.base.md#static-bufferify)
+* [hexZeroPad](_src_base_.base.md#static-hexzeropad)
 * [isHexString](_src_base_.base.md#static-ishexstring)
 * [linearSearch](_src_base_.base.md#static-linearsearch)
 * [print](_src_base_.base.md#static-print)
@@ -126,6 +129,20 @@ Name | Type | Description |
 
 ___
 
+###  bigNumberify
+
+▸ **bigNumberify**(`value`: any): *BigInt*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`value` | any |
+
+**Returns:** *BigInt*
+
+___
+
 ###  binarySearch
 
 ▸ **binarySearch**(`array`: Buffer[], `element`: Buffer, `compareFunction`: function): *number*
@@ -293,6 +310,20 @@ tree.print()
 
 ___
 
+### `Static` bigNumberify
+
+▸ **bigNumberify**(`value`: any): *BigInt*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`value` | any |
+
+**Returns:** *BigInt*
+
+___
+
 ### `Static` binarySearch
 
 ▸ **binarySearch**(`array`: Buffer[], `element`: Buffer, `compareFunction`: function): *number*
@@ -380,6 +411,21 @@ Name | Type |
 
 ___
 
+### `Static` hexZeroPad
+
+▸ **hexZeroPad**(`hexStr`: string, `length`: number): *string*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`hexStr` | string |
+`length` | number |
+
+**Returns:** *string*
+
+___
+
 ### `Static` isHexString
 
 ▸ **isHexString**(`v`: string): *boolean*
diff --git a/docs/classes/_src_merklemountainrange_.merklemountainrange.md b/docs/classes/_src_merklemountainrange_.merklemountainrange.md
index 299a8ff..47e351d 100644
--- a/docs/classes/_src_merklemountainrange_.merklemountainrange.md
+++ b/docs/classes/_src_merklemountainrange_.merklemountainrange.md
@@ -34,6 +34,7 @@
 * [_log2](_src_merklemountainrange_.merklemountainrange.md#protected-_log2)
 * [_zip](_src_merklemountainrange_.merklemountainrange.md#protected-_zip)
 * [append](_src_merklemountainrange_.merklemountainrange.md#append)
+* [bigNumberify](_src_merklemountainrange_.merklemountainrange.md#bignumberify)
 * [binarySearch](_src_merklemountainrange_.merklemountainrange.md#binarysearch)
 * [bufferToHex](_src_merklemountainrange_.merklemountainrange.md#buffertohex)
 * [bufferify](_src_merklemountainrange_.merklemountainrange.md#bufferify)
@@ -61,9 +62,11 @@
 * [print](_src_merklemountainrange_.merklemountainrange.md#print)
 * [rollUp](_src_merklemountainrange_.merklemountainrange.md#rollup)
 * [verify](_src_merklemountainrange_.merklemountainrange.md#verify)
+* [bigNumberify](_src_merklemountainrange_.merklemountainrange.md#static-bignumberify)
 * [binarySearch](_src_merklemountainrange_.merklemountainrange.md#static-binarysearch)
 * [bufferToHex](_src_merklemountainrange_.merklemountainrange.md#static-buffertohex)
 * [bufferify](_src_merklemountainrange_.merklemountainrange.md#static-bufferify)
+* [hexZeroPad](_src_merklemountainrange_.merklemountainrange.md#static-hexzeropad)
 * [isHexString](_src_merklemountainrange_.merklemountainrange.md#static-ishexstring)
 * [linearSearch](_src_merklemountainrange_.merklemountainrange.md#static-linearsearch)
 * [print](_src_merklemountainrange_.merklemountainrange.md#static-print)
@@ -254,6 +257,22 @@ Name | Type |
 
 ___
 
+###  bigNumberify
+
+▸ **bigNumberify**(`value`: any): *BigInt*
+
+*Inherited from [Base](_src_base_.base.md).[bigNumberify](_src_base_.base.md#bignumberify)*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`value` | any |
+
+**Returns:** *BigInt*
+
+___
+
 ###  binarySearch
 
 ▸ **binarySearch**(`array`: Buffer[], `element`: Buffer, `compareFunction`: function): *number*
@@ -760,6 +779,22 @@ Name | Type |
 
 ___
 
+### `Static` bigNumberify
+
+▸ **bigNumberify**(`value`: any): *BigInt*
+
+*Inherited from [Base](_src_base_.base.md).[bigNumberify](_src_base_.base.md#bignumberify)*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`value` | any |
+
+**Returns:** *BigInt*
+
+___
+
 ### `Static` binarySearch
 
 ▸ **binarySearch**(`array`: Buffer[], `element`: Buffer, `compareFunction`: function): *number*
@@ -853,6 +888,23 @@ Name | Type |
 
 ___
 
+### `Static` hexZeroPad
+
+▸ **hexZeroPad**(`hexStr`: string, `length`: number): *string*
+
+*Inherited from [Base](_src_base_.base.md).[hexZeroPad](_src_base_.base.md#static-hexzeropad)*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`hexStr` | string |
+`length` | number |
+
+**Returns:** *string*
+
+___
+
 ### `Static` isHexString
 
 ▸ **isHexString**(`v`: string): *boolean*
diff --git a/docs/classes/_src_merkletree_.merkletree.md b/docs/classes/_src_merkletree_.merkletree.md
index 3670ee6..8fec91c 100644
--- a/docs/classes/_src_merkletree_.merkletree.md
+++ b/docs/classes/_src_merkletree_.merkletree.md
@@ -27,10 +27,12 @@ Class reprensenting a Merkle Tree
 * [_zip](_src_merkletree_.merkletree.md#protected-_zip)
 * [addLeaf](_src_merkletree_.merkletree.md#addleaf)
 * [addLeaves](_src_merkletree_.merkletree.md#addleaves)
+* [bigNumberify](_src_merkletree_.merkletree.md#bignumberify)
 * [binarySearch](_src_merkletree_.merkletree.md#binarysearch)
 * [bufferToHex](_src_merkletree_.merkletree.md#buffertohex)
 * [bufferify](_src_merkletree_.merkletree.md#bufferify)
 * [bufferifyFn](_src_merkletree_.merkletree.md#bufferifyfn)
+* [combineHashes](_src_merkletree_.merkletree.md#combinehashes)
 * [getDepth](_src_merkletree_.merkletree.md#getdepth)
 * [getHexLayers](_src_merkletree_.merkletree.md#gethexlayers)
 * [getHexLayersFlat](_src_merkletree_.merkletree.md#gethexlayersflat)
@@ -64,10 +66,12 @@ Class reprensenting a Merkle Tree
 * [verify](_src_merkletree_.merkletree.md#verify)
 * [verifyMultiProof](_src_merkletree_.merkletree.md#verifymultiproof)
 * [verifyMultiProofWithFlags](_src_merkletree_.merkletree.md#verifymultiproofwithflags)
+* [bigNumberify](_src_merkletree_.merkletree.md#static-bignumberify)
 * [binarySearch](_src_merkletree_.merkletree.md#static-binarysearch)
 * [bufferToHex](_src_merkletree_.merkletree.md#static-buffertohex)
 * [bufferify](_src_merkletree_.merkletree.md#static-bufferify)
 * [getMultiProof](_src_merkletree_.merkletree.md#static-getmultiproof)
+* [hexZeroPad](_src_merkletree_.merkletree.md#static-hexzeropad)
 * [isHexString](_src_merkletree_.merkletree.md#static-ishexstring)
 * [linearSearch](_src_merkletree_.merkletree.md#static-linearsearch)
 * [marshalLeaves](_src_merkletree_.merkletree.md#static-marshalleaves)
@@ -282,6 +286,22 @@ Name | Type | Default |
 
 ___
 
+###  bigNumberify
+
+▸ **bigNumberify**(`value`: any): *BigInt*
+
+*Inherited from [Base](_src_base_.base.md).[bigNumberify](_src_base_.base.md#bignumberify)*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`value` | any |
+
+**Returns:** *BigInt*
+
+___
+
 ###  binarySearch
 
 ▸ **binarySearch**(`array`: Buffer[], `element`: Buffer, `compareFunction`: function): *number*
@@ -400,6 +420,20 @@ Name | Type |
 
 ___
 
+###  combineHashes
+
+▸ **combineHashes**(`hashes`: Buffer[]): *any*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`hashes` | Buffer[] |
+
+**Returns:** *any*
+
+___
+
 ###  getDepth
 
 ▸ **getDepth**(): *number*
@@ -1141,6 +1175,22 @@ Name | Type |
 
 ___
 
+### `Static` bigNumberify
+
+▸ **bigNumberify**(`value`: any): *BigInt*
+
+*Inherited from [Base](_src_base_.base.md).[bigNumberify](_src_base_.base.md#bignumberify)*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`value` | any |
+
+**Returns:** *BigInt*
+
+___
+
 ### `Static` binarySearch
 
 ▸ **binarySearch**(`array`: Buffer[], `element`: Buffer, `compareFunction`: function): *number*
@@ -1262,6 +1312,23 @@ Name | Type | Description |
 
 ___
 
+### `Static` hexZeroPad
+
+▸ **hexZeroPad**(`hexStr`: string, `length`: number): *string*
+
+*Inherited from [Base](_src_base_.base.md).[hexZeroPad](_src_base_.base.md#static-hexzeropad)*
+
+**Parameters:**
+
+Name | Type |
+------ | ------ |
+`hexStr` | string |
+`length` | number |
+
+**Returns:** *string*
+
+___
+
 ### `Static` isHexString
 
 ▸ **isHexString**(`v`: string): *boolean*
diff --git a/docs/interfaces/_src_merkletree_.options.md b/docs/interfaces/_src_merkletree_.options.md
index c26abfa..a477885 100644
--- a/docs/interfaces/_src_merkletree_.options.md
+++ b/docs/interfaces/_src_merkletree_.options.md
@@ -11,6 +11,7 @@
 ### Properties
 
 * [complete](_src_merkletree_.options.md#optional-complete)
+* [concatenator](_src_merkletree_.options.md#optional-concatenator)
 * [duplicateOdd](_src_merkletree_.options.md#optional-duplicateodd)
 * [fillDefaultHash](_src_merkletree_.options.md#optional-filldefaulthash)
 * [hashLeaves](_src_merkletree_.options.md#optional-hashleaves)
@@ -29,6 +30,12 @@ If set to `true`, the resulting tree will be a complete tree. Recommended for us
 
 ___
 
+### `Optional` concatenator
+
+• **concatenator**? : *any*
+
+___
+
 ### `Optional` duplicateOdd
 
 • **duplicateOdd**? : *boolean*
diff --git a/docs/modules/_src_merkletree_.md b/docs/modules/_src_merkletree_.md
index 9f65526..c952ab7 100644
--- a/docs/modules/_src_merkletree_.md
+++ b/docs/modules/_src_merkletree_.md
@@ -76,4 +76,4 @@ ___
 
 ###  TValue
 
-Ƭ **TValue**: *Buffer | string | number | null | undefined*
+Ƭ **TValue**: *Buffer | BigInt | string | number | null | undefined*
diff --git a/src/MerkleTree.ts b/src/MerkleTree.ts
index d446f81..e738dc3 100644
--- a/src/MerkleTree.ts
+++ b/src/MerkleTree.ts
@@ -32,7 +32,7 @@ export interface Options {
   /** If set to `true`, the resulting tree will be a complete tree. Recommended for use of multiProofs. */
   complete?: boolean;
 
-  concatFn?: any
+  concatenator?: any
 }
 
 /**
@@ -42,7 +42,7 @@ export interface Options {
 export class MerkleTree extends Base {
   private duplicateOdd: boolean = false
   private hashFn: THashFn
-  private concatFn: any = Buffer.concat
+  private concatenator: any = Buffer.concat
   private hashLeaves: boolean = false
   private isBitcoinTree: boolean = false
   private leaves: TLeaf[] = []
@@ -111,8 +111,8 @@ export class MerkleTree extends Base {
 
     this.duplicateOdd = !!options.duplicateOdd
 
-    if (options.concatFn) {
-      this.concatFn = options.concatFn
+    if (options.concatenator) {
+      this.concatenator = options.concatenator
     }
 
     this.hashFn = this.bufferifyFn(hashFn)
@@ -1454,7 +1454,7 @@ export class MerkleTree extends Base {
 
   combineHashes (hashes: Buffer[]) {
     hashes = hashes.filter(x => x.byteLength > 0)
-    return this.concatFn(hashes)
+    return this.concatenator(hashes)
   }
 }
 
diff --git a/test/MerkleTree.test.js b/test/MerkleTree.test.js
index 32d5646..6c620e6 100644
--- a/test/MerkleTree.test.js
+++ b/test/MerkleTree.test.js
@@ -1342,7 +1342,7 @@ test('poseidon hash', async t => {
 
   const leaves = [1, 2, 3, 4].map(x => poseidonHash([x]))
   const tree = new MerkleTree(leaves, poseidonHash, {
-    concatFn: (hashes) => hashes
+    concatenator: (hashes) => hashes
   })
   t.equal(tree.getHexRoot(), '0xd24e045226875e22b37ce607ea2af7a9fbb137ee128caa0ce3663615350245')