diff --git a/packages/ui-app/src/Params/Param/BaseBytes.tsx b/packages/ui-app/src/Params/Param/BaseBytes.tsx
index 8253395aa3..60629798d2 100644
--- a/packages/ui-app/src/Params/Param/BaseBytes.tsx
+++ b/packages/ui-app/src/Params/Param/BaseBytes.tsx
@@ -5,8 +5,9 @@
 import { Props as BaseProps, Size } from '../types';
 
 import React from 'react';
-
 import hexToU8a from '@polkadot/util/hex/toU8a';
+import bnToU8a from '@polkadot/util/bn/toU8a';
+import u8aConcat from '@polkadot/util/u8a/concat';
 
 import Input from '../../Input';
 import Bare from './Bare';
@@ -14,7 +15,8 @@ import Bare from './Bare';
 type Props = BaseProps & {
   length?: number,
   size?: Size,
-  validate?: (u8a: Uint8Array) => boolean
+  validate?: (u8a: Uint8Array) => boolean,
+  withLength?: boolean
 };
 
 const defaultValidate = (u8a: Uint8Array): boolean =>
@@ -44,9 +46,9 @@ export default class BaseBytes extends React.PureComponent<Props> {
   }
 
   onChange = (hex: string): void => {
-    const { length = -1, onChange, validate = defaultValidate } = this.props;
+    const { length = -1, onChange, validate = defaultValidate, withLength = false } = this.props;
 
-    let u8a;
+    let u8a: Uint8Array;
 
     try {
       u8a = hexToU8a(hex);
@@ -57,10 +59,16 @@ export default class BaseBytes extends React.PureComponent<Props> {
     const isValidLength = length !== -1
       ? u8a.length === length
       : u8a.length !== 0;
+    const isValid = isValidLength && validate(u8a);
 
     onChange({
-      isValid: isValidLength && validate(u8a),
-      value: u8a
+      isValid,
+      value: u8aConcat(
+        withLength
+          ? bnToU8a(u8a.length, 32, true)
+          : new Uint8Array([]),
+        u8a
+      )
     });
   }
 }
diff --git a/packages/ui-app/src/Params/Param/Bytes.tsx b/packages/ui-app/src/Params/Param/Bytes.tsx
index 34dc6715e3..273d103ac7 100644
--- a/packages/ui-app/src/Params/Param/Bytes.tsx
+++ b/packages/ui-app/src/Params/Param/Bytes.tsx
@@ -8,20 +8,25 @@ import React from 'react';
 
 import BaseBytes from './BaseBytes';
 
-export default function Bytes ({ className, defaultValue, isDisabled, isError, label, name, onChange, style, withLabel }: Props) {
-  return (
-    <BaseBytes
-      className={className}
-      defaultValue={defaultValue}
-      isDisabled={isDisabled}
-      isError={isError}
-      label={label}
-      length={-1}
-      name={name}
-      onChange={onChange}
-      size='full'
-      style={style}
-      withLabel={withLabel}
-    />
-  );
+export default class Bytes extends React.PureComponent<Props> {
+  render () {
+    const { className, defaultValue, isDisabled, isError, label, name, onChange, style, withLabel } = this.props;
+
+    return (
+      <BaseBytes
+        className={className}
+        defaultValue={defaultValue}
+        isDisabled={isDisabled}
+        isError={isError}
+        label={label}
+        length={-1}
+        name={name}
+        onChange={onChange}
+        size='full'
+        style={style}
+        withLabel={withLabel}
+        withLength
+      />
+    );
+  }
 }