diff --git a/.changeset/fuzzy-donuts-double.md b/.changeset/fuzzy-donuts-double.md
new file mode 100644
index 0000000..2ba9639
--- /dev/null
+++ b/.changeset/fuzzy-donuts-double.md
@@ -0,0 +1,9 @@
+---
+"esbuild-cf-functions-plugin": patch
+---
+
+Changed the output format to ES modules.
+
+This should always result in smaller output file sizes!
+
+For example, the example function went from `1.3kb` to `0.45kb`!
diff --git a/src/plugin.ts b/src/plugin.ts
index 98cd26f..2a9a9cc 100644
--- a/src/plugin.ts
+++ b/src/plugin.ts
@@ -20,7 +20,7 @@ export const CloudFrontFunctionsPlugin = (): Plugin => ({
 
   setup: (build) => {
     build.initialOptions.target = "es5"
-    build.initialOptions.format = "cjs"
+    build.initialOptions.format = "esm"
 
     if (build.initialOptions.minify) {
       build.initialOptions.minify = false