diff --git a/src/action.ts b/src/action.ts
index 2f655a2..da8a580 100644
--- a/src/action.ts
+++ b/src/action.ts
@@ -13,7 +13,7 @@ import { downloadTool, extractZip } from "@actions/tool-cache";
 import { getExecOutput } from "@actions/exec";
 import { writeBunfig } from "./bunfig";
 import { saveState } from "@actions/core";
-import { retry } from "./utils";
+import { addExtension, retry } from "./utils";
 
 export type Input = {
   customUrl?: string;
@@ -119,7 +119,7 @@ async function downloadBun(
   url: string,
   bunPath: string
 ): Promise<string | undefined> {
-  const zipPath = await downloadTool(url);
+  const zipPath = addExtension(await downloadTool(url), ".zip");
   const extractedZipPath = await extractZip(zipPath);
   const extractedBunPath = await extractBun(extractedZipPath);
   try {
diff --git a/src/utils.ts b/src/utils.ts
index 26a7c6b..e757dc9 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,6 +1,6 @@
 import { debug, warning } from "@actions/core";
 import { info } from "node:console";
-import { existsSync, readFileSync } from "node:fs";
+import { existsSync, readFileSync, renameSync } from "node:fs";
 import { join, basename } from "node:path";
 
 export function retry<T>(
@@ -18,6 +18,15 @@ export function retry<T>(
   });
 }
 
+export function addExtension(path: string, ext: string): string {
+  if (!path.endsWith(ext)) {
+    renameSync(path, path + ext);
+    return path + ext;
+  }
+
+  return path;
+}
+
 const FILE_VERSION_READERS = {
   "package.json": (content: string) =>
     JSON.parse(content).packageManager?.split("bun@")?.[1],