diff --git a/src/download.ts b/src/download.ts
index 74918f3d27917197f4dce589937d0d8fa9956226..6515c40223fec909f9f80e5721b82ed1e4d87fcc 100644
--- a/src/download.ts
+++ b/src/download.ts
@@ -10,7 +10,7 @@ import { existsSync } from "node:fs";
 import { createRequire } from "node:module";
 import { dirname, join } from "node:path";
 import { fileURLToPath } from "node:url";
-import { getLibFilename, getNpmPackageName } from "./platform";
+import { getLibFilename, getNpmPackageName } from "./platform.js";
 
 /**
  * Get the current file's directory
diff --git a/src/ffi.ts b/src/ffi.ts
index 0a9f3b075a8153db8fbad9593cb1ebd5938279f1..3599a15d9da40ca0e78850651ac3b7e1952ba230 100644
--- a/src/ffi.ts
+++ b/src/ffi.ts
@@ -17,8 +17,8 @@ import {
   ptr,
   read,
 } from "bun:ffi";
-import { findBinary } from "./download";
-import { embeddedLibPath } from "./embedded";
+import { findBinary } from "./download.js";
+import { embeddedLibPath } from "./embedded.js";
 import type {
   DirItem,
   DirSearchResult,
@@ -34,8 +34,8 @@ import type {
   SearchResult,
   WatchEvent,
   WatchEventKind,
-} from "./fff-api";
-import { createGrepCursor, err } from "./fff-api";
+} from "./fff-api.js";
+import { createGrepCursor, err } from "./fff-api.js";
 
 /** Grep mode constants matching the C API (u8). */
 const GREP_MODE_PLAIN = 0;
diff --git a/src/finder.ts b/src/finder.ts
index d8210b43f4502527a2356fb0c3de837bc909ac97..31724f6a8aee51f76c76c5ebd6de5e12f3fafd99 100644
--- a/src/finder.ts
+++ b/src/finder.ts
@@ -36,7 +36,7 @@ import {
   isAvailable,
   type NativeHandle,
   readWatchEventBatch,
-} from "./ffi";
+} from "./ffi.js";
 
 import type {
   DirSearchOptions,
@@ -56,9 +56,9 @@ import type {
   WatchBatchCallback,
   WatchOptions,
   WatchUnsubscribe,
-} from "./fff-api";
+} from "./fff-api.js";
 
-import { err } from "./fff-api";
+import { err } from "./fff-api.js";
 
 /**
  * FileFinder - Fast file finder with fuzzy search
diff --git a/src/index.ts b/src/index.ts
index 3b54b82d03bd5d37f3665d59c91273dc62118c1b..17bf456ea78d6b1f432d514f12eb430cc8bfcab1 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,4 +1,4 @@
-export { binaryExists, findBinary } from "./download";
+export { binaryExists, findBinary } from "./download.js";
 export type {
   DbHealth,
   DirItem,
@@ -29,12 +29,12 @@ export type {
   WatchEventKind,
   WatchOptions,
   WatchUnsubscribe,
-} from "./fff-api";
+} from "./fff-api.js";
 
-export { FileFinder } from "./finder";
+export { FileFinder } from "./finder.js";
 export {
   getLibExtension,
   getLibFilename,
   getNpmPackageName,
   getTriple,
-} from "./platform";
+} from "./platform.js";