diff --git a/.changeset/early-news-taste.md b/.changeset/early-news-taste.md
new file mode 100644
index 000000000000..72aeb2178275
--- /dev/null
+++ b/.changeset/early-news-taste.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare': patch
+---
+
+use posix to resolve relative path
diff --git a/packages/adapter-cloudflare/index.js b/packages/adapter-cloudflare/index.js
index c1be491f5972..8f6061f4efe2 100644
--- a/packages/adapter-cloudflare/index.js
+++ b/packages/adapter-cloudflare/index.js
@@ -1,5 +1,5 @@
 import { writeFileSync } from 'fs';
-import { relative } from 'path';
+import { posix } from 'path';
 import { fileURLToPath } from 'url';
 import * as esbuild from 'esbuild';
 
@@ -21,7 +21,7 @@ export default function (options = {}) {
 
 			const { paths } = await builder.prerender({ dest });
 
-			const relativePath = relative(tmp, builder.getServerDirectory());
+			const relativePath = posix.relative(tmp, builder.getServerDirectory());
 
 			writeFileSync(
 				`${tmp}/manifest.js`,