diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7e2b5d06f..937615969 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ All notable changes to casper-js-sdk.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 2.5.2
+
+### Fixed
+
+- Problem when serializing U128, U256 ad U512 `toBytes`.
+
 ## 2.5.1
 
 ### Fixed
diff --git a/package.json b/package.json
index 98b84553e..795ff96f5 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "casper-js-sdk",
-  "version": "2.5.1",
+  "version": "2.5.2",
   "license": "Apache 2.0",
   "description": "SDK to interact with the Casper blockchain",
   "homepage": "https://github.com/casper-ecosystem/casper-js-sdk#README.md",
diff --git a/src/lib/ByteConverters.ts b/src/lib/ByteConverters.ts
index fc68ff991..c23c6e4d9 100644
--- a/src/lib/ByteConverters.ts
+++ b/src/lib/ByteConverters.ts
@@ -35,6 +35,10 @@ export const toBytesNumber = (bitSize: number, signed: boolean) => (
   if (valTwos.gte(0)) {
     // for positive number, we had to deal with paddings
     if (bitSize > 64) {
+      // if zero just return zero
+      if (valTwos.eq(0)) {
+        return bytes;
+      }
       // for u128, u256, u512, we have to and append extra byte for length
       return concat([bytes, Uint8Array.from([bytes.length])])
         .slice()
diff --git a/test/lib/byterepr.test.ts b/test/lib/byterepr.test.ts
index ec5bc3d8b..c66abdbf1 100644
--- a/test/lib/byterepr.test.ts
+++ b/test/lib/byterepr.test.ts
@@ -12,9 +12,21 @@ import {
   AccessRights,
   decodeBase16
 } from '../../src';
-import { toBytesDeployHash } from '../../src/lib/ByteConverters';
+import { toBytesNumber, toBytesDeployHash } from '../../src/lib/ByteConverters';
 
 describe(`numbers' toBytes`, () => {
+  it('CLU256 of zero after serialization should be equal to [0]', () => {
+    const toBytesNum128 = toBytesNumber(128, false);
+    const toBytesNum256 = toBytesNumber(256, false);
+    const toBytesNum512= toBytesNumber(512, false);
+
+    const expectedRes = Uint8Array.from([0]);
+
+    expect(toBytesNum128(0)).to.deep.eq(expectedRes)
+    expect(toBytesNum256(0)).to.deep.eq(expectedRes)
+    expect(toBytesNum512(0)).to.deep.eq(expectedRes)
+  });
+
   it('should be able to serialize/deserialize u8', () => {
     const validBytes = Uint8Array.from([0x0a]);
     const clVal = CLValueBuilder.u8(10);