diff --git a/packages/shared/src/utils.ts b/packages/shared/src/utils.ts
index 918fc11e0..f9f67bdd5 100644
--- a/packages/shared/src/utils.ts
+++ b/packages/shared/src/utils.ts
@@ -24,9 +24,9 @@ export const toBase64 = (bytes: Uint8Array): string =>
 export const fromBase64 = (str: string): Uint8Array =>
   Uint8Array.from(atob(str), (c) => c.charCodeAt(0));
 
-export const base64ToU8Receiver = (_key: string, value: unknown) => {
-  if (typeof value === 'string' && value.startsWith('base64:')) {
-    return fromBase64(value.split('base64:')[1]);
+export const hexToU8Receiver = (_key: string, value: unknown) => {
+  if (typeof value === 'string' && value.startsWith('0x')) {
+    return fromHexString(value);
   }
   return value;
 };
@@ -44,22 +44,22 @@ const sortedReplacer = (_key: string, value: unknown) => {
   return value;
 };
 
-const u8ToBase64Replacer = (_key: string, value: unknown) => {
+const u8ToHexReplacer = (_key: string, value: unknown) => {
   if (value instanceof Uint8Array) {
-    return `base64:${toBase64(value)}`;
+    return `0x${toHexString(value)}`;
   }
   return value;
 };
 
 const sortedSerializingReplacer = (_key: string, value: unknown): unknown => {
-  const serializedValue = u8ToBase64Replacer(_key, value);
+  const serializedValue = u8ToHexReplacer(_key, value);
   return sortedReplacer(_key, serializedValue);
 };
 
 export const toJSON = (obj: unknown) =>
   JSON.stringify(obj, sortedSerializingReplacer);
 
-export const fromJSON = (json: string) => JSON.parse(json, base64ToU8Receiver);
+export const fromJSON = (json: string) => JSON.parse(json, hexToU8Receiver);
 
 export const zip = <T, Z>(
   a: ReadonlyArray<T>,
diff --git a/packages/taco/test/conditions/context.test.ts b/packages/taco/test/conditions/context.test.ts
index dd9064f50..6a1e85965 100644
--- a/packages/taco/test/conditions/context.test.ts
+++ b/packages/taco/test/conditions/context.test.ts
@@ -3,6 +3,7 @@ import { fakeProvider, fakeSigner } from '@nucypher/test-utils';
 import { ethers } from 'ethers';
 import { beforeAll, describe, expect, it } from 'vitest';
 
+import { toBytes, toHexString } from '../../src';
 import {
   ConditionExpression,
   ContractCondition,
@@ -65,6 +66,20 @@ describe('context', () => {
     const conditionExpr = new ConditionExpression(contractCondition);
     const context = conditionExpr.buildContext(provider, {}, signer);
 
+    describe('custom parameters', () => {
+      it("serializes bytes as hex strings", async () => {
+        const customParamsWithBytes: Record<string, CustomContextParam> = {};
+        const customParam = toBytes('hello');
+        // Uint8Array is not a valid CustomContextParam, override the type:
+        customParamsWithBytes[customParamKey] = customParam as unknown as string;
+
+        const asJson = await context.withCustomParams(customParamsWithBytes).toJson();
+        const asObj = JSON.parse(asJson);
+        expect(asObj).toBeDefined();
+        expect(asObj[customParamKey]).toEqual(`0x${toHexString(customParam)}`);
+      });
+    });
+
     describe('return value test', () => {
       it('accepts on a custom context parameters', async () => {
         const asObj = await context.withCustomParams(customParams).toObj();