diff --git a/doc/api/http.md b/doc/api/http.md
index 22fe2c43eef729..aaeb9403ff499b 100644
--- a/doc/api/http.md
+++ b/doc/api/http.md
@@ -1598,6 +1598,7 @@ header name:
 `last-modified`, `location`, `max-forwards`, `proxy-authorization`, `referer`,
 `retry-after`, or `user-agent` are discarded.
 * `set-cookie` is always an array. Duplicates are added to the array.
+* For duplicate `cookie` headers, the values are joined together with '; '.
 * For all other headers, the values are joined together with ', '.
 
 ### message.httpVersion
diff --git a/doc/api/http2.md b/doc/api/http2.md
index ad7b59d4e87147..c5a2382a479f6a 100644
--- a/doc/api/http2.md
+++ b/doc/api/http2.md
@@ -2297,7 +2297,7 @@ For incoming headers:
 `upgrade-insecure-requests`, `user-agent` or `x-content-type-options` are
 discarded.
 * `set-cookie` is always an array. Duplicates are added to the array.
-* `cookie`: the values are joined together with '; '.
+* For duplicate `cookie` headers, the values are joined together with '; '.
 * For all other headers, the values are joined together with ', '.
 
 ```js