diff --git a/packages/protocols/README.md b/packages/protocols/README.md
index 4a0a440..f089dde 100644
--- a/packages/protocols/README.md
+++ b/packages/protocols/README.md
@@ -66,12 +66,11 @@ import { generateMerkleProof } from "@zk-kit/protocols"
 
 const depth = 20
 const zeroValue = BigInt(0)
-const arity = 2
 const identity = new ZkIdentity()
 const identityCommitment = identity.genIdentityCommitment()
 const identityCommitments = [BigInt(1), identityCommitment, BigInt(2)]
 
-const merkleProof = generateMerkleProof(depth, zeroValue, arity, identityCommitments, 1)
+const merkleProof = generateMerkleProof(depth, zeroValue, identityCommitments, 1)
 ```
 
 ### Creating Semaphore proofs
diff --git a/packages/protocols/src/utils.ts b/packages/protocols/src/utils.ts
index c3b85d8..f895aab 100644
--- a/packages/protocols/src/utils.ts
+++ b/packages/protocols/src/utils.ts
@@ -29,17 +29,11 @@ export function genExternalNullifier(plaintext: string): string {
  * Creates a Merkle tree.
  * @param depth The depth of the tree.
  * @param zeroValue The zero value of the tree.
- * @param arity The number of leaves per node.
  * @param leaves The list of the leaves of the tree.
  * @returns The Merkle tree.
  */
-export function generateMerkleTree(
-  depth: number,
-  zeroValue: StrBigInt,
-  arity: number,
-  leaves: StrBigInt[]
-): IncrementalMerkleTree {
-  const tree = new IncrementalMerkleTree(poseidon, depth, zeroValue, arity)
+export function generateMerkleTree(depth: number, zeroValue: StrBigInt, leaves: StrBigInt[]): IncrementalMerkleTree {
+  const tree = new IncrementalMerkleTree(poseidon, depth, zeroValue, 2)
 
   for (const leaf of leaves) {
     tree.insert(BigInt(leaf))
@@ -52,7 +46,6 @@ export function generateMerkleTree(
  * Creates a Merkle proof.
  * @param depth The depth of the tree.
  * @param zeroValue The zero value of the tree.
- * @param arity The number of leaves per node.
  * @param leaves The list of the leaves of the tree.
  * @param leaf The leaf for which Merkle proof should be created.
  * @returns The Merkle proof.
@@ -60,13 +53,12 @@ export function generateMerkleTree(
 export function generateMerkleProof(
   depth: number,
   zeroValue: StrBigInt,
-  arity: number,
   leaves: StrBigInt[],
   leaf: StrBigInt
 ): MerkleProof {
   if (leaf === zeroValue) throw new Error("Can't generate a proof for a zero leaf")
 
-  const tree = generateMerkleTree(depth, zeroValue, arity, leaves)
+  const tree = generateMerkleTree(depth, zeroValue, leaves)
 
   const leafIndex = tree.leaves.indexOf(BigInt(leaf))
 
@@ -76,10 +68,7 @@ export function generateMerkleProof(
 
   const merkleProof = tree.createProof(leafIndex)
 
-  if (arity === 2) {
-    // It makes it compatible with the parameter in the contracts.
-    merkleProof.siblings = merkleProof.siblings.map((s) => s[0])
-  }
+  merkleProof.siblings = merkleProof.siblings.map((s) => s[0])
 
   return merkleProof
 }
diff --git a/packages/protocols/tests/rln.test.ts b/packages/protocols/tests/rln.test.ts
index 7f88508..ff1c16d 100644
--- a/packages/protocols/tests/rln.test.ts
+++ b/packages/protocols/tests/rln.test.ts
@@ -41,7 +41,7 @@ describe("RLN", () => {
       const epoch: string = genExternalNullifier("test-epoch")
       const rlnIdentifier = RLN.genIdentifier()
 
-      const merkleProof = generateMerkleProof(15, BigInt(0), 2, leaves, identityCommitment)
+      const merkleProof = generateMerkleProof(15, BigInt(0), leaves, identityCommitment)
       const witness = RLN.genWitness(secretHash, merkleProof, epoch, signal, rlnIdentifier)
 
       expect(typeof witness).toBe("object")
@@ -52,7 +52,7 @@ describe("RLN", () => {
       const leaves = Object.assign([], identityCommitments)
       leaves.push(zeroIdCommitment)
 
-      const fun = () => generateMerkleProof(15, zeroIdCommitment, 2, leaves, zeroIdCommitment)
+      const fun = () => generateMerkleProof(15, zeroIdCommitment, leaves, zeroIdCommitment)
 
       expect(fun).toThrow("Can't generate a proof for a zero leaf")
     })
@@ -90,7 +90,7 @@ describe("RLN", () => {
       const epoch = genExternalNullifier("test-epoch")
       const rlnIdentifier = RLN.genIdentifier()
 
-      const merkleProof = generateMerkleProof(15, BigInt(0), 2, leaves, identityCommitment)
+      const merkleProof = generateMerkleProof(15, BigInt(0), leaves, identityCommitment)
       const witness = RLN.genWitness(secretHash, merkleProof, epoch, signal, rlnIdentifier)
 
       const vkeyPath = path.join(zkeyFiles, "rln", "verification_key.json")
diff --git a/packages/protocols/tests/semaphore.test.ts b/packages/protocols/tests/semaphore.test.ts
index a7b20ce..6a3ffa2 100644
--- a/packages/protocols/tests/semaphore.test.ts
+++ b/packages/protocols/tests/semaphore.test.ts
@@ -26,7 +26,7 @@ describe("Semaphore", () => {
       const leaves = [BigInt(3), BigInt(2), identityCommitment, BigInt(4)]
       const signal = "0x111"
 
-      const merkleProof = generateMerkleProof(20, BigInt(0), 2, leaves, identityCommitment)
+      const merkleProof = generateMerkleProof(20, BigInt(0), leaves, identityCommitment)
 
       const witness = Semaphore.genWitness(
         identity.getTrapdoor(),
@@ -47,7 +47,7 @@ describe("Semaphore", () => {
       const leaves = [BigInt(3), BigInt(2), identityCommitment, BigInt(4)]
       const signal = "0x111"
 
-      const merkleProof = generateMerkleProof(20, BigInt(0), 2, leaves, identityCommitment)
+      const merkleProof = generateMerkleProof(20, BigInt(0), leaves, identityCommitment)
 
       const witness = Semaphore.genWitness(
         identity.getTrapdoor(),