diff --git a/README.md b/README.md
index dfb21ec..7a8b0ea 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ $ npm i @fastify/aws-lambda
 | property                       | description                                                                                                                          | default value |
 | ------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------ | ------------- |
 | binaryMimeTypes                | Array of binary MimeTypes to handle                                                                                                  | `[]`          |
-| enforceBase64                  | Function that receives the reply and returns a boolean indicating if the response content is binary or not and should be base64-encoded                          | `undefined`   |
+| enforceBase64                  | Function that receives the response and returns a boolean indicating if the response content is binary or not and should be base64-encoded                          | `undefined`   |
 | serializeLambdaArguments       | Activate the serialization of lambda Event and Context in http header `x-apigateway-event` `x-apigateway-context`                    | `false` *(was `true` for <v2.0.0)*        |
 | decorateRequest       | Decorates the fastify request with the lambda Event and Context `request.awsLambda.event` `request.awsLambda.context`                    | `true`        |
 | decorationPropertyName       | The default property name for request decoration                    | `awsLambda`        |
diff --git a/index.d.ts b/index.d.ts
index 85dce04..ef59626 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,5 +1,5 @@
 import { Context } from "aws-lambda";
-import { FastifyInstance, FastifyReply } from "fastify";
+import { FastifyInstance, LightMyRequestResponse } from "fastify";
 
 export interface LambdaFastifyOptions {
   binaryMimeTypes?: string[];
@@ -7,7 +7,7 @@ export interface LambdaFastifyOptions {
   serializeLambdaArguments?: boolean;
   decorateRequest?: boolean;
   decorationPropertyName?: string;
-  enforceBase64?: (reply: FastifyReply) => boolean;
+  enforceBase64?: (response: LightMyRequestResponse) => boolean;
 }
 
 export interface LambdaResponse {
diff --git a/index.test-d.ts b/index.test-d.ts
index 4926e6b..f70bc61 100644
--- a/index.test-d.ts
+++ b/index.test-d.ts
@@ -1,4 +1,4 @@
-import fastify from "fastify";
+import fastify, {LightMyRequestResponse} from "fastify";
 import awsLambdaFastify, {
   PromiseHandler,
   CallbackHandler,
@@ -70,7 +70,10 @@ expectAssignable<LambdaFastifyOptions>({
   serializeLambdaArguments: false,
   decorateRequest: true,
   decorationPropertyName: "myAWSstuff",
-  enforceBase64: (reply) => false,
+  enforceBase64: (response) => {
+      expectType<LightMyRequestResponse>(response);
+      return false;
+  },
 });
 
 expectError(awsLambdaFastify());
diff --git a/test/basic.test.js b/test/basic.test.js
index 82d55e5..ec4d402 100644
--- a/test/basic.test.js
+++ b/test/basic.test.js
@@ -138,7 +138,7 @@ test('GET with custom binary check response', async (t) => {
   const proxy = awsLambdaFastify(app, {
     binaryMimeTypes: [],
     serializeLambdaArguments: true,
-    enforceBase64: (reply) => reply.headers['x-base64-encoded'] === '1'
+    enforceBase64: (response) => response.headers['x-base64-encoded'] === '1'
   })
   const ret = await proxy({
     httpMethod: 'GET',