diff --git a/libs/wingsdk/src/shared/bundling.ts b/libs/wingsdk/src/shared/bundling.ts
index 0d38bc855e8..c8c702696c4 100644
--- a/libs/wingsdk/src/shared/bundling.ts
+++ b/libs/wingsdk/src/shared/bundling.ts
@@ -7,7 +7,6 @@ import { normalPath } from "./misc";
 const SDK_PATH = normalPath(resolve(__dirname, "..", ".."));
 
 export interface Bundle {
-  entrypointPath: string;
   directory: string;
   hash: string;
   outfilePath: string;
@@ -87,7 +86,6 @@ export function createBundle(
     .digest("hex");
 
   return {
-    entrypointPath: outfile,
     directory: outdir,
     hash: codeHash,
     outfilePath: outfile,
diff --git a/libs/wingsdk/src/target-sim/function.inflight.ts b/libs/wingsdk/src/target-sim/function.inflight.ts
index 2234b4bdd8a..39b4c252a4c 100644
--- a/libs/wingsdk/src/target-sim/function.inflight.ts
+++ b/libs/wingsdk/src/target-sim/function.inflight.ts
@@ -147,7 +147,7 @@ export class Function implements IFunctionClient, ISimulatorResourceInstance {
       throw new Error("Bundle not created");
     }
 
-    return new Sandbox(this.bundle.entrypointPath, {
+    return new Sandbox(this.bundle.outfilePath, {
       env: {
         ...this.env,
         WING_SIMULATOR_CALLER: this.context.resourceHandle,
diff --git a/libs/wingsdk/src/target-sim/service.inflight.ts b/libs/wingsdk/src/target-sim/service.inflight.ts
index 5531e34a23f..f75733d7cbb 100644
--- a/libs/wingsdk/src/target-sim/service.inflight.ts
+++ b/libs/wingsdk/src/target-sim/service.inflight.ts
@@ -82,7 +82,7 @@ export class Service implements IServiceClient, ISimulatorResourceInstance {
       return;
     }
 
-    this.sandbox = new Sandbox(this.bundle.entrypointPath, {
+    this.sandbox = new Sandbox(this.bundle.outfilePath, {
       env: {
         ...this.environmentVariables,
         WING_SIMULATOR_URL: this.context.serverUrl,
diff --git a/libs/wingsdk/src/target-tf-azure/function.ts b/libs/wingsdk/src/target-tf-azure/function.ts
index 6c321583526..d4c8ff89393 100644
--- a/libs/wingsdk/src/target-tf-azure/function.ts
+++ b/libs/wingsdk/src/target-tf-azure/function.ts
@@ -192,7 +192,7 @@ export class Function extends cloud.Function {
     // Move index.js to function name directory. Every Azure function in a function app
     // must be in its own folder containing an index.js and function.json files
     fs.mkdirSync(`${codeDir}/${this.functionName}`);
-    fs.renameSync(bundle.entrypointPath, `${outDir}/index.js`);
+    fs.renameSync(bundle.outfilePath, `${outDir}/index.js`);
 
     // As per documentation "a function must have exactly one trigger" so for now
     // by default a function will support http get requests
diff --git a/libs/wingsdk/src/target-tf-gcp/function.ts b/libs/wingsdk/src/target-tf-gcp/function.ts
index 93c99cae51c..01fa62bb869 100644
--- a/libs/wingsdk/src/target-tf-gcp/function.ts
+++ b/libs/wingsdk/src/target-tf-gcp/function.ts
@@ -1,5 +1,5 @@
 import { writeFileSync } from "fs";
-import { join } from "path";
+import { join, basename } from "path";
 import { AssetType, Lazy, TerraformAsset } from "cdktf";
 import { Construct } from "constructs";
 import { App } from "./app";
@@ -197,7 +197,7 @@ export class Function extends cloud.Function {
       packageJson,
       JSON.stringify(
         {
-          main: "index.js",
+          main: basename(bundle.outfilePath),
           dependencies: {
             "@google-cloud/functions-framework": "^3.0.0",
             "@google-cloud/datastore": "8.4.0",
diff --git a/libs/wingsdk/test/target-tf-gcp/function.test.ts b/libs/wingsdk/test/target-tf-gcp/function.test.ts
index 31be648b562..4886e151d08 100644
--- a/libs/wingsdk/test/target-tf-gcp/function.test.ts
+++ b/libs/wingsdk/test/target-tf-gcp/function.test.ts
@@ -1,3 +1,5 @@
+import { readdirSync, readFileSync, existsSync } from "fs";
+import { join } from "path";
 import * as cdktf from "cdktf";
 import { test, expect } from "vitest";
 import { Function } from "../../src/cloud";
@@ -24,6 +26,22 @@ test("basic function", () => {
   new Function(app, "Function", inflight);
   const output = app.synth();
 
+  const functionOutDir = readdirSync(app.workdir, {
+    recursive: true,
+    withFileTypes: true,
+  }).find((d) => d.isDirectory())!;
+  const packageJson = JSON.parse(
+    readFileSync(
+      join(app.workdir, functionOutDir.name, "package.json"),
+      "utf-8"
+    )
+  );
+  const indexFilename = "index.cjs";
+  expect(packageJson.main).toBe(indexFilename);
+  expect(
+    existsSync(join(app.workdir, functionOutDir.name, indexFilename))
+  ).toBeTruthy();
+
   // THEN
   expect(tfResourcesOf(output)).toEqual([
     "google_cloudfunctions_function",