diff --git a/.changeset/old-houses-film.md b/.changeset/old-houses-film.md
new file mode 100644
index 00000000..0b55ed27
--- /dev/null
+++ b/.changeset/old-houses-film.md
@@ -0,0 +1,7 @@
+---
+'@edge-runtime/cookies': minor
+'edge-runtime': path
+---
+
+feat(cookies): expose splitCookiesString function
+fix: splitting cookies when concatenated
diff --git a/packages/cookies/src/index.ts b/packages/cookies/src/index.ts
index 58b4c784..57ae5867 100644
--- a/packages/cookies/src/index.ts
+++ b/packages/cookies/src/index.ts
@@ -1,4 +1,9 @@
 export type { CookieListItem, RequestCookie, ResponseCookie } from './types'
 export { RequestCookies } from './request-cookies'
 export { ResponseCookies } from './response-cookies'
-export { stringifyCookie, parseCookie, parseSetCookie } from './serialize'
+export {
+  stringifyCookie,
+  parseCookie,
+  parseSetCookie,
+  splitCookiesString,
+} from './serialize'
diff --git a/packages/runtime/package.json b/packages/runtime/package.json
index 3655f281..5a291def 100644
--- a/packages/runtime/package.json
+++ b/packages/runtime/package.json
@@ -24,6 +24,7 @@
     "web"
   ],
   "dependencies": {
+    "@edge-runtime/cookies": "workspace:*",
     "@edge-runtime/format": "workspace:*",
     "@edge-runtime/ponyfill": "workspace:*",
     "@edge-runtime/vm": "workspace:*",
diff --git a/packages/runtime/src/server/create-handler.ts b/packages/runtime/src/server/create-handler.ts
index 5cff7636..e7bdc39e 100644
--- a/packages/runtime/src/server/create-handler.ts
+++ b/packages/runtime/src/server/create-handler.ts
@@ -2,6 +2,7 @@ import type { EdgeRuntime } from '../edge-runtime'
 import type { IncomingMessage, ServerResponse } from 'http'
 import type { Logger, NodeHeaders } from '../types'
 import type { EdgeContext } from '@edge-runtime/vm'
+import { splitCookiesString } from '@edge-runtime/cookies'
 import { getClonableBodyStream, pipeBodyStreamToResponse } from './body-streams'
 import prettyMs from 'pretty-ms'
 import timeSpan from 'time-span'
@@ -112,13 +113,15 @@ function toRequestInitHeaders(req: IncomingMessage): RequestInit['headers'] {
 
 /**
  * Transforms WHATWG Headers into a Node Headers shape. Copies all items but
- * does a special case for Set-Cookie using the [`getSetCookie`](https://developer.mozilla.org/en-US/docs/Web/API/Headers/getSetCookie) method.
+ * does a special case for Set-Cookie header field-values are sometimes comma joined in one string. This splits them without choking on commas
+ * that are within a single set-cookie field-value, such as in the Expires portion.
  */
 function toNodeHeaders(headers?: Headers): NodeHeaders {
   const result: NodeHeaders = {}
   if (headers) {
     for (const [key, value] of headers.entries()) {
-      result[key] = key === 'set-cookie' ? headers.getSetCookie() : value
+      result[key] =
+        key?.toLowerCase() === 'set-cookie' ? splitCookiesString(value) : value
     }
   }
   return result
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index e9133853..77895581 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1,5 +1,9 @@
 lockfileVersion: '6.0'
 
+settings:
+  autoInstallPeers: true
+  excludeLinksFromLockfile: false
+
 importers:
 
   .:
@@ -240,6 +244,9 @@ importers:
 
   packages/runtime:
     dependencies:
+      '@edge-runtime/cookies':
+        specifier: workspace:*
+        version: link:../cookies
       '@edge-runtime/format':
         specifier: workspace:*
         version: link:../format
@@ -8645,7 +8652,3 @@ packages:
   /zwitch@2.0.4:
     resolution: {integrity: sha512-bXE4cR/kVZhKZX/RjPEflHaKVhUVl85noU3v6b8apfQEc1x4A+zBxjZ4lN8LqGd6WZ3dl98pY4o717VFmoPp+A==}
     dev: false
-
-settings:
-  autoInstallPeers: true
-  excludeLinksFromLockfile: false