diff --git a/lib/cookie.js b/lib/cookie.js
index e6c84a9..a3a2e65 100644
--- a/lib/cookie.js
+++ b/lib/cookie.js
@@ -29,7 +29,7 @@ export function serialize(key, val, opts) {
   if (opts.hasOwnProperty('expires') && opts.expires) {
     // pairs.push('Expires=' + opts.expires.toUTCString())
     // 有效期, 已不建议使用,改用 max-age
-    if (Date.isDate(opts.expires)) {
+    if (opts.expires instanceof Date) {
       opts.maxAge = ~~(opts.expires.getTime() / 1000)
     } else {
       opts.maxAge = +opts.expires
diff --git a/package.json b/package.json
index d9ff047..543484d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@gm5/response",
-  "version": "2.0.1",
+  "version": "2.0.2",
   "type": "module",
   "description": "对Http的response进一步封装, 提供常用的API",
   "main": "index.js",
@@ -11,7 +11,7 @@
     "http"
   ],
   "dependencies": {
-    "iofs": "^1.5.0"
+    "iofs": "^1.5.3"
   },
   "repository": "https://git.wkit.fun/gm5/response.git",
   "license": "MIT"