diff --git a/index.bs b/index.bs
index d250db9..898c264 100644
--- a/index.bs
+++ b/index.bs
@@ -27,8 +27,8 @@ Level: 1
 
 <pre class=anchors>
 spec: ecma262; urlPrefix: https://tc39.github.io/ecma262/
-    type: dfn
-        text: time values; url: sec-time-values-and-time-range
+    type: dfn; text: time values; url: sec-time-values-and-time-range
+    type: dfn; text: ToString; url: sec-tostring
 </pre>
 
 <pre class=link-defaults>
@@ -490,6 +490,7 @@ dictionary CookieInit {
   USVString path = "/";
   CookieSameSite sameSite = "strict";
   boolean partitioned = false;
+  long long? maxAge = null;
 };
 
 dictionary CookieStoreDeleteOptions {
@@ -658,8 +659,9 @@ The <dfn method for=CookieStore>set(|name|, |value|)</dfn> method steps are:
         null,
         null,
         "`/`",
-        "{{CookieSameSite/strict}}", and
-        false.
+        "{{CookieSameSite/strict}}",
+        false, and
+        null.
     1. If |r| is failure, then [=reject=] |p| with a {{TypeError}} and abort these steps.
     1. [=/Resolve=] |p| with undefined.
 1. Return |p|.
@@ -682,8 +684,9 @@ The <dfn method for=CookieStore>set(|options|)</dfn> method steps are:
         |options|["{{CookieInit/expires}}"],
         |options|["{{CookieInit/domain}}"],
         |options|["{{CookieInit/path}}"],
-        |options|["{{CookieInit/sameSite}}"], and
-        |options|["{{CookieInit/partitioned}}"].
+        |options|["{{CookieInit/sameSite}}"],
+        |options|["{{CookieInit/partitioned}}"], and
+        |options|["{{CookieInit/maxAge}}"].
     1. If |r| is failure, then [=reject=] |p| with a {{TypeError}} and abort these steps.
     1. [=/Resolve=] |p| with undefined.
 1. Return |p|.
@@ -992,15 +995,6 @@ The <dfn attribute for=ServiceWorkerGlobalScope>cookieStore</dfn> getter steps a
 <!-- ============================================================ -->
 
 
-<div algorithm>
-To represent a date and time |dateTime| <dfn>as a timestamp</dfn>,
-return the number of milliseconds from 00:00:00 UTC, 1 January 1970 to |dateTime|
-(assuming that there are exactly 86,400,000 milliseconds per day).
-
-Note: This is the same representation used for [=time values=] in [[ECMAScript]].
-</div>
-
-
 <div algorithm>
 To <dfn>date serialize</dfn> a {{DOMHighResTimeStamp}} |millis|,
 let |dateTime| be the date and time |millis| milliseconds after 00:00:00 UTC, 1 January 1970
@@ -1061,8 +1055,9 @@ To <dfn>set a cookie</dfn> given a [=/URL=] |url|,
 {{DOMHighResTimeStamp}}-or-null |expires|,
 [=/scalar value string=]-or-null |domain|,
 [=/scalar value string=] |path|,
-[=/string=] |sameSite|, and
-[=/boolean=] |partitioned|:
+[=/string=] |sameSite|,
+[=/boolean=] |partitioned|, and
+[=/64-bit signed integer=]-or-null |maxAge|:
 
 1. [=Normalize=] |name|.
 1. [=Normalize=] |value|.
@@ -1090,7 +1085,10 @@ To <dfn>set a cookie</dfn> given a [=/URL=] |url|,
     1. Let |encodedDomain| be the result of [=UTF-8 encode|UTF-8 encoding=] |parsedDomain|.
     1. If the [=byte sequence=] [=byte sequence/length=] of |encodedDomain| is greater than the [=cookie/maximum attribute value size=], then return failure.
     1. [=list/Append=] (\``Domain`\`, |encodedDomain|) to |attributes|.
-1. If |expires| is non-null, then [=list/append=] (\``Expires`\`, |expires| ([=date serialized=])) to |attributes|.
+1. If |expires| is non-null:
+    1. If |maxAge| is non-null, then return failure.
+    1. [=list/Append=] (\``Expires`\`, |expires| ([=date serialized=])) to |attributes|.
+1. Otherwise, if |maxAge| is non-null, then [=list/append=] (\``Max-Age`\`, [=ToString=](|maxAge|)) to |attributes|.
 1. If |path| is the empty string, then set |path| to the [=/serialized cookie default path=] of |url|.
 1. If |path| does not start with U+002F (/), then return failure.
 1. If |path| is not U+002F (/), and |name|, [=byte-lowercased=], [=byte sequence/starts with=] \``__host-`\`, then return failure.
@@ -1107,7 +1105,7 @@ To <dfn>set a cookie</dfn> given a [=/URL=] |url|,
         : "{{CookieSameSite/lax}}"
         :: [=list/Append=] (\``SameSite`\`, \``Lax`\`) to |attributes|.
     </dl>
-1. If |partitioned| is true, [=list/Append=] (``Partitioned`\`, \`\`) to |attributes|.
+1. If |partitioned| is true, [=list/Append=] (\``Partitioned`\`, \`\`) to |attributes|.
 1. Perform the steps defined in [[RFC6265BIS-14#name-storage-model|Cookies § Storage Model]] for when the user agent "receives a cookie" with
     |url| as <var ignore>request-uri</var>,
     |encodedName| as <var ignore>cookie-name</var>,
@@ -1136,26 +1134,19 @@ a [=/URL=] |url|,
 [=/scalar value string=] |path|, and
 [=/boolean=] |partitioned|:
 
-1. Let |expires| be the earliest representable date represented [=as a timestamp=].
-
-    Note: The exact value of |expires| is not important for the purposes of this algorithm,
-    as long as it is in the past.
-
 1. [=Normalize=] |name|.
-
 1. Let |value| be the empty string.
-
 1. If |name|'s [=string/length=] is 0, then set |value| to any non-empty [=implementation-defined=] string.
-
 1. Return the results of running [=set a cookie=] with
     |url|,
     |name|,
     |value|,
-    |expires|,
+    null,
     |domain|,
     |path|,
-    "{{CookieSameSite/strict}}", and
-    |partitioned|.
+    "{{CookieSameSite/strict}}",
+    |partitioned|,
+    and 0.
 
 </div>