diff --git a/valuescript-npm/package.json b/valuescript-npm/package.json
index 1049f2d..505032f 100644
--- a/valuescript-npm/package.json
+++ b/valuescript-npm/package.json
@@ -1,6 +1,6 @@
 {
   "name": "valuescript",
-  "version": "0.0.3",
+  "version": "0.0.4",
   "description": "A dialect of TypeScript with value semantics",
   "main": "dist/index.js",
   "scripts": {
diff --git a/valuescript-npm/src/WorkerPool.ts b/valuescript-npm/src/WorkerPool.ts
index 31eaf5e..32e4189 100644
--- a/valuescript-npm/src/WorkerPool.ts
+++ b/valuescript-npm/src/WorkerPool.ts
@@ -21,7 +21,9 @@ export default class WorkerPool {
   }
 
   async use<T>(fn: (worker: Worker, terminate: () => void) => T): Promise<T> {
-    return await this.#semaphore.use(async () => {
+    const release = await this.#semaphore.acquire();
+
+    try {
       let bestSlot = this.#slots[0];
 
       for (let i = 1; i < this.size; i++) {
@@ -48,7 +50,14 @@ export default class WorkerPool {
         );
       }
 
-      return await bestSlot.use(fn);
-    });
+      return await bestSlot.use((worker, terminate) => {
+        return fn(worker, () => {
+          terminate();
+          release();
+        });
+      });
+    } finally {
+      release();
+    }
   }
 }