diff --git a/plugins/css_bundler/src/bundler.ts b/plugins/css_bundler/src/bundler.ts
index e9c5d37..22469ec 100644
--- a/plugins/css_bundler/src/bundler.ts
+++ b/plugins/css_bundler/src/bundler.ts
@@ -1,6 +1,6 @@
 import { fromFileUrl, join } from '$std/path/mod.ts'
 import { builder } from './builder.ts'
-import { cssImports, Logger } from './helpers.ts'
+import { cssImports, Logger, uInt8ArrayConcat } from './helpers.ts'
 
 export async function bundleCss(
 	sourceDir: string,
@@ -24,7 +24,7 @@ export async function bundleCss(
 			)
 			await Deno.writeFile(
 				join(assetDir, pathname),
-				Uint8Array.of(...code, ...sourceMappingURL),
+				uInt8ArrayConcat(code, sourceMappingURL),
 			)
 
 			await Deno.writeFile(
diff --git a/plugins/css_bundler/src/helpers.ts b/plugins/css_bundler/src/helpers.ts
index 070728a..9f55cda 100644
--- a/plugins/css_bundler/src/helpers.ts
+++ b/plugins/css_bundler/src/helpers.ts
@@ -26,3 +26,10 @@ export async function hashFile(file: ArrayBuffer): Promise<string> {
 }
 
 export const cssImports: Map<string, string> = new Map()
+
+export function uInt8ArrayConcat(a: Uint8Array, b: Uint8Array) {
+	const dest = new Uint8Array(a.length + b.length)
+	dest.set(a)
+	dest.set(b, a.length)
+	return dest
+}