diff --git a/package.json b/package.json
index 25f94e3..9f0ab72 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@drop/droplet",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "main": "index.js",
   "types": "index.d.ts",
   "napi": {
diff --git a/src/manifest.rs b/src/manifest.rs
index 261362a..cd711a8 100644
--- a/src/manifest.rs
+++ b/src/manifest.rs
@@ -1,14 +1,17 @@
 use std::{
   fs::File,
   io::{BufRead, BufReader},
-  path::Path,
+  path::Path, thread,
 };
 
 #[cfg(unix)]
 use std::os::unix::fs::PermissionsExt;
 
 use gxhash::gxhash128;
-use napi::{Error, JsFunction, JsNumber};
+use napi::{
+  threadsafe_function::{ErrorStrategy, ThreadsafeFunction, ThreadsafeFunctionCallMode},
+  Error, JsFunction,
+};
 use serde::Serialize;
 use serde_json::json;
 use uuid::Uuid;
@@ -26,6 +29,19 @@ struct Chunk {
   checksum: String,
 }
 
+#[napi]
+pub fn call_alt_thread_func(callback: JsFunction) -> Result<(), Error> {
+  let tsfn: ThreadsafeFunction<u32, ErrorStrategy::CalleeHandled> = callback
+    .create_threadsafe_function(0, |ctx| {
+      ctx.env.create_uint32(ctx.value + 1).map(|v| vec![v])
+    })?;
+  let tsfn = tsfn.clone();
+  thread::spawn(move || {
+    tsfn.call(Ok(0), ThreadsafeFunctionCallMode::Blocking);
+  });
+  Ok(())
+}
+
 #[napi]
 pub fn generate_manifest(
   dir: String,