diff --git a/src/poseidon.js b/src/poseidon.js
index db1c7065..90076d7b 100644
--- a/src/poseidon.js
+++ b/src/poseidon.js
@@ -1,10 +1,11 @@
 const assert = require("assert");
-const Scalar = require("ffjavascript").Scalar;
-const ZqField = require("ffjavascript").ZqField;
-const { unstringifyBigInts } = require("ffjavascript").utils;
+const bn128 = require("snarkjs").bn128;
+const bigInt = require("snarkjs").bigInt;
+const F = bn128.Fr;
+const { unstringifyBigInts } = require("snarkjs");
 
 // Prime 0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001
-const F = new ZqField(Scalar.fromString("21888242871839275222246405745257275088548364400416034343698204186575808495617"));
+// const F = new ZqField(Scalar.fromString("21888242871839275222246405745257275088548364400416034343698204186575808495617"));
 
 // Parameters are generated by a reference script https://extgit.iaik.tugraz.at/krypto/hadeshash/-/blob/master/code/generate_parameters_grain.sage
 // Used like so: sage generate_parameters_grain.sage 1 0 254 2 8 56 0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001
@@ -26,7 +27,7 @@ function poseidon(inputs) {
     const nRoundsF = N_ROUNDS_F;
     const nRoundsP = N_ROUNDS_P[t - 2];
 
-    let state = [...inputs.map(a => F.e(a)), F.zero];
+    let state = [...inputs.map(a => bigInt(a)), F.zero];
     for (let r = 0; r < nRoundsF + nRoundsP; r++) {
         state = state.map((a, i) => F.add(a, C[t - 2][r * t + i]));
         
@@ -43,7 +44,7 @@ function poseidon(inputs) {
             );
         }
     }
-    return F.normalize(state[0]);
+    return F.affine(state[0]);
 }
 
 module.exports = poseidon;
diff --git a/src/poseidon_gencontract.js b/src/poseidon_gencontract.js
index c7143053..4019b94e 100644
--- a/src/poseidon_gencontract.js
+++ b/src/poseidon_gencontract.js
@@ -3,7 +3,7 @@
 //
 
 const Contract = require("./evmasm");
-const { unstringifyBigInts } = require("ffjavascript").utils;
+const { unstringifyBigInts } = require("snarkjs");
 
 const { C:K, M } = unstringifyBigInts(require("./poseidon_constants.json"));
 
diff --git a/src/smt_hashes_poseidon.js b/src/smt_hashes_poseidon.js
index 67a080e5..2c20266c 100644
--- a/src/smt_hashes_poseidon.js
+++ b/src/smt_hashes_poseidon.js
@@ -1,8 +1,6 @@
 const poseidon = require("./poseidon");
 const bigInt = require("snarkjs").bigInt;
 
-//const F = new ZqField(Scalar.fromString("21888242871839275222246405745257275088548364400416034343698204186575808495617"));
-
 exports.hash0 = function (left, right) {
     return poseidon([left, right]);
 };
@@ -10,5 +8,3 @@ exports.hash0 = function (left, right) {
 exports.hash1 = function(key, value) {
     return poseidon([key, value, bigInt.one]);
 };
-
-//exports.F = poseidon.F;
diff --git a/test/poseidoncircuit.js b/test/poseidoncircuit.js
index 201025d1..a046b5fa 100644
--- a/test/poseidoncircuit.js
+++ b/test/poseidoncircuit.js
@@ -1,6 +1,7 @@
 const chai = require("chai");
 const path = require("path");
-const tester = require("circom").tester;
+const snarkjs = require("snarkjs");
+const compiler = require("circom");
 
 const poseidon = require("../src/poseidon.js");
 
@@ -12,25 +13,30 @@ describe("Poseidon Circuit test", function () {
 
     this.timeout(100000);
 
-    before(async () => {
-        circuit2 = await tester(path.join(__dirname, "circuits", "poseidon2_test.circom"));
-        circuit4 = await tester(path.join(__dirname, "circuits", "poseidon4_test.circom"));
+    before( async () => {
+        const cirDef2 = await compiler(path.join(__dirname, "circuits", "poseidon2_test.circom"));
+        const cirDef4 = await compiler(path.join(__dirname, "circuits", "poseidon4_test.circom"));
+
+        circuit2 = new snarkjs.Circuit(cirDef2);
+        circuit4 = new snarkjs.Circuit(cirDef4);
     });
 
     it("Should check constrain of hash([1, 2])", async () => {
         const hash = poseidon([1, 2]);
         assert.equal("17117985411748610629288516079940078114952304104811071254131751175361957805920", hash.toString());
         const w = await circuit2.calculateWitness({inputs: [1, 2]}, true);
-        await circuit2.assertOut(w, {out : hash});
-        await circuit2.checkConstraints(w);
+        const res = w[circuit2.getSignalIdx("main.out")];
+        assert.equal(res.toString(), hash.toString());
+        await circuit2.checkWitness(w);
     });
 
     it("Should check constrain of hash([3, 4])", async () => {
         const hash = poseidon([3, 4]);
         assert.equal("21867347236198497199818917118739170715216974132230970409806500217655788551452", hash.toString());
         const w = await circuit2.calculateWitness({inputs: [3, 4]});
-        await circuit2.assertOut(w, {out : hash});
-        await circuit2.checkConstraints(w);
+        const res = w[circuit2.getSignalIdx("main.out")];
+        assert.equal(res.toString(), hash.toString());
+        await circuit2.checkWitness(w);
     });
 
 
@@ -38,15 +44,17 @@ describe("Poseidon Circuit test", function () {
         const hash = poseidon([1, 2, 3, 4]);
         assert.equal("10501812514110530158422365608831771203648472822841727510887411206067265790462", hash.toString());
         const w = await circuit4.calculateWitness({inputs: [1, 2, 3, 4]});
-        await circuit4.assertOut(w, {out : hash});
-        await circuit4.checkConstraints(w);
+        const res = w[circuit4.getSignalIdx("main.out")];
+        assert.equal(res.toString(), hash.toString());
+        await circuit4.checkWitness(w);
     });
 
     it("Should check constrain of hash([5, 6, 7, 8])", async () => {
         const hash = poseidon([5, 6, 7, 8]);
         assert.equal("20761996991478317428195238015626872345373101531750069996451149877836620406299", hash.toString());
         const w = await circuit4.calculateWitness({inputs: [5, 6, 7, 8]});
-        await circuit4.assertOut(w, {out : hash});
-        await circuit4.checkConstraints(w);
+        const res = w[circuit4.getSignalIdx("main.out")];
+        assert.equal(res.toString(), hash.toString());
+        await circuit4.checkWitness(w);
     });
 });