diff --git a/index.js b/index.js
index 7a156fb..f0206cc 100644
--- a/index.js
+++ b/index.js
@@ -10,7 +10,7 @@ function md5(str) {
 async function getResponse(cacheDirPath, requestArguments, bodyFunctionName) {
   const [url, requestInit, ...rest] = requestArguments;
   const requestParams = requestInit.body
-    ? Object.assign({}, requestInit, {body: typeof requestInit.body === 'object' ? requestInit.body.toString() : requestInit.body})
+    ? ({ ...requestInit, body: typeof requestInit.body === 'object' ? requestInit.body.toString() : requestInit.body })
     : requestInit;
 
   const cacheHash = md5(JSON.stringify([url, requestParams, ...rest]) + bodyFunctionName);