diff --git a/6-data-storage/01-cookie/article.md b/6-data-storage/01-cookie/article.md
index ba1ffa71..0f2e3d1b 100644
--- a/6-data-storage/01-cookie/article.md
+++ b/6-data-storage/01-cookie/article.md
@@ -310,7 +310,7 @@ function setCookie(name, value, options = {}) {
     ...options
   };
 
-  if (options.expires && options.expires.toUTCString) {
+  if (options.expires instanceof Date) {
     options.expires = options.expires.toUTCString();
   }
 
diff --git a/6-data-storage/01-cookie/cookie.js b/6-data-storage/01-cookie/cookie.js
index 7d8eebf3..cd3e17c0 100644
--- a/6-data-storage/01-cookie/cookie.js
+++ b/6-data-storage/01-cookie/cookie.js
@@ -13,7 +13,7 @@ function setCookie(name, value, options = {}) {
     ...options
   };
 
-  if (options.expires.toUTCString) {
+  if (options.expires instanceof Date) {
     options.expires = options.expires.toUTCString();
   }