diff --git a/packages/adapter-cloudflare-workers/index.js b/packages/adapter-cloudflare-workers/index.js
index e47af92ff445f..ef18d54d1e23d 100644
--- a/packages/adapter-cloudflare-workers/index.js
+++ b/packages/adapter-cloudflare-workers/index.js
@@ -55,7 +55,7 @@ export default function () {
 				entryPoints: [`${tmp}/entry.js`],
 				outfile: `${entrypoint}/index.js`,
 				bundle: true,
-				target: 'es2020',
+				target: 'es2019',
 				platform: 'browser'
 			});