diff --git a/benchmark/index.ts b/benchmark/index.ts
index a42cfc4..5a993c2 100644
--- a/benchmark/index.ts
+++ b/benchmark/index.ts
@@ -3,7 +3,7 @@ import { PerformanceObserver, PerformanceEntry, PerformanceObserverEntryList, pe
 
 import { HMAC } from './../src/index.js';
 
-type TransformedEntry = {
+interface TransformedEntry {
     operations: number,
     duration: number,
     throughput: string
diff --git a/tests/unit.test.ts b/tests/unit.test.ts
index c004abb..7b597a0 100644
--- a/tests/unit.test.ts
+++ b/tests/unit.test.ts
@@ -1,33 +1,29 @@
 /* eslint-disable @typescript-eslint/ban-ts-comment */
-import { Request, Response } from 'express';
+import { request, Request, Response } from 'express';
 
 import { HMAC, AuthError } from './../src/index.js';
 
-type MockRequest = {
+interface MockRequest {
     headers?: {
         authorization?: string
     }
     method?: 'GET' | 'POST',
     originalUrl?: string,
-    body?: Record<string, unknown> | number[],
+    body?: Record<string, unknown> | unknown[]
 }
 
-type Spies = {
+interface Spies {
     next: jest.Mock
 }
 
-function mockedRequest(override?: MockRequest): Partial<Request> {
-    return {
-        headers: {
-            authorization: 'HMAC 1573504737300:76251c6323fbf6355f23816a4c2e12edfd10672517104763ab1b10f078277f86'
-        },
-        method: 'POST',
-        originalUrl: '/api/order',
-        body: {
-            foo: 'bar'
-        },
-        ...override || {},
-    };
+function mockedRequest(override: MockRequest = {}): Partial<Request> {
+    const req = request;
+    req.headers = override.headers ?? { authorization: 'HMAC 1573504737300:76251c6323fbf6355f23816a4c2e12edfd10672517104763ab1b10f078277f86' };
+    req.method = override.method ?? 'POST';
+    req.originalUrl = override.originalUrl ?? '/api/order';
+    req.body = override.body ?? { foo: 'bar' };
+
+    return req;
 }
 
 describe('unit', () => {
@@ -47,7 +43,7 @@ describe('unit', () => {
 
         middleware(mockedRequest() as Request, {} as Response, spies.next);
 
-        expect(spies.next).toHaveBeenLastCalledWith();
+        expect(spies.next).toHaveBeenCalledWith();
 
         global.Date.now = originalDateNow;
     });
@@ -60,7 +56,7 @@ describe('unit', () => {
 
         middleware(mockedRequest({ headers: { authorization: 'HMAC 1573504737300:4f1c59c68f09af0790b4531118438ae179689eebc5bb30a8359719e319f70b85' }, body: [1, 2, 3] }) as Request, {} as Response, spies.next);
 
-        expect(spies.next).toHaveBeenLastCalledWith();
+        expect(spies.next).toHaveBeenCalledWith();
 
         global.Date.now = originalDateNow;
     });
@@ -73,7 +69,7 @@ describe('unit', () => {
 
         middleware(mockedRequest({ headers: { authorization: 'HMAC 1573504737300:b55d3ad0b64e106655871bbe7e0d1f55a1f81f7b' }}) as Request, {} as Response, spies.next);
 
-        expect(spies.next).toHaveBeenLastCalledWith();
+        expect(spies.next).toHaveBeenCalledWith();
 
         global.Date.now = originalDateNow;
     });
@@ -91,7 +87,7 @@ describe('unit', () => {
             body: undefined
         }) as Request, {} as Response, spies.next);
 
-        expect(spies.next).toHaveBeenLastCalledWith();
+        expect(spies.next).toHaveBeenCalledWith();
 
         global.Date.now = originalDateNow;
     });
@@ -201,7 +197,7 @@ describe('unit', () => {
 
         middleware(mockedRequest() as Request, {} as Response, spies.next);
 
-        expect(spies.next).toHaveBeenLastCalledWith();
+        expect(spies.next).toHaveBeenCalledWith();
 
         global.Date.now = originalDateNow;
     });
@@ -229,7 +225,7 @@ describe('unit', () => {
 
         middleware(mockedRequest() as Request, {} as Response, spies.next);
 
-        expect(spies.next).toHaveBeenLastCalledWith();
+        expect(spies.next).toHaveBeenCalledWith();
 
         global.Date.now = originalDateNow;
     });
@@ -249,6 +245,71 @@ describe('unit', () => {
         global.Date.now = originalDateNow;
     });
 
+    test('passes hmac with empty object as body', () => {
+        const originalDateNow = Date.now.bind(global.Date);
+        global.Date.now = () => 1573504737300;
+        
+        const middleware = HMAC('secret');
+
+        middleware(mockedRequest({ body: {} }) as Request, {} as Response, spies.next);
+
+        expect(spies.next).toHaveBeenCalledWith();
+
+        global.Date.now = originalDateNow;
+    });
+
+    test('passes hmac with basic object as body', () => {
+        const originalDateNow = Date.now.bind(global.Date);
+        global.Date.now = () => 1573504737300;
+        
+        const middleware = HMAC('secret');
+
+        middleware(mockedRequest({ body: { foo: 'bar' } }) as Request, {} as Response, spies.next);
+
+        expect(spies.next).toHaveBeenCalledWith();
+
+        global.Date.now = originalDateNow;
+    });
+
+    test('passes hmac with complex object as body', () => {
+        const originalDateNow = Date.now.bind(global.Date);
+        global.Date.now = () => 1573504737300;
+        
+        const middleware = HMAC('secret');
+
+        middleware(mockedRequest({ body: { foo: 'bar', baz: { fizz: 1, buzz: [1, 2] } } }) as Request, {} as Response, spies.next);
+
+        expect(spies.next).toHaveBeenCalledWith();
+
+        global.Date.now = originalDateNow;
+    });
+
+    test('passes hmac with empty array as body', () => {
+        const originalDateNow = Date.now.bind(global.Date);
+        global.Date.now = () => 1573504737300;
+        
+        const middleware = HMAC('secret');
+
+        middleware(mockedRequest({ body: [] }) as Request, {} as Response, spies.next);
+
+        expect(spies.next).toHaveBeenCalledWith();
+
+        global.Date.now = originalDateNow;
+    });
+
+    test('passes hmac with array as body', () => {
+        const originalDateNow = Date.now.bind(global.Date);
+        global.Date.now = () => 1573504737300;
+        
+        const middleware = HMAC('secret');
+
+        middleware(mockedRequest({ body: [1, 'test', {}, ['a', {}]] }) as Request, {} as Response, spies.next);
+
+        expect(spies.next).toHaveBeenCalledWith();
+
+        global.Date.now = originalDateNow;
+    });
+
     // Some users aren't going to be using TS, we need to ensure these test still work even though you can't expose the error if you use TS
     
     test('passing incorrect secret throws an error', () => {