diff --git a/types/types.d.ts b/types/types.d.ts
index 8e22f1e..1c504f7 100644
--- a/types/types.d.ts
+++ b/types/types.d.ts
@@ -174,7 +174,10 @@ declare namespace fastifySession {
     cookiePrefix?: string;
   }
 
-  export interface CookieOptions extends Omit<CookieSerializeOptions, 'signed'> {}
+  export interface CookieOptions extends Omit<CookieSerializeOptions, 'signed' | 'maxAge'> {
+    /** A `number` in milliseconds that specifies the `Expires` attribute by adding the specified milliseconds to the current date. If both `expires` and `maxAge` are set, then `expires` is used. */
+    maxAge?: number;
+  }
 
   export class MemoryStore implements fastifySession.SessionStore {
     constructor(map?: Map<string, Fastify.Session>);
diff --git a/types/types.test-d.ts b/types/types.test-d.ts
index dd17422..a37e32f 100644
--- a/types/types.test-d.ts
+++ b/types/types.test-d.ts
@@ -7,8 +7,8 @@ import fastify, {
   Session
 } from 'fastify';
 import Redis from 'ioredis';
-import { expectAssignable, expectError, expectType } from 'tsd';
-import { MemoryStore, SessionStore, default as fastifySession, default as plugin } from '..';
+import { expectAssignable, expectDocCommentIncludes, expectError, expectType } from 'tsd';
+import { CookieOptions, MemoryStore, SessionStore, default as fastifySession, default as plugin } from '..';
 
 class EmptyStore {
   set(_sessionId: string, _session: any, _callback: Function) {}
@@ -46,9 +46,14 @@ app.register(plugin, {
 app.register(plugin, {
   secret,
   cookie: {
+    maxAge: 1000,
     secure: 'auto'
   }
 });
+
+const cookieMaxAge: CookieOptions = {};
+expectDocCommentIncludes<"millisecond">(cookieMaxAge.maxAge);
+
 app.register(plugin, {
   secret,
   store: new EmptyStore()