diff --git a/async.ts b/async.ts
index 1a8ef7b..62275dc 100644
--- a/async.ts
+++ b/async.ts
@@ -104,7 +104,7 @@ export function channel<T = void>(): Channel<T> {
 }
 
 channel.sender = function sender<T>(
-  f: (recv: Receiver<T>) => void | PromiseLike<void>,
+  f: (recv: Receiver<T>) => void | PromiseLike<void>
 ): Sender<T> {
   const { send, recv } = channel<T>();
   Promise.resolve(f(recv)).then(noop).then(recv.close, recv.close);
@@ -112,7 +112,7 @@ channel.sender = function sender<T>(
 };
 
 channel.receiver = function receiver<T>(
-  f: (send: Sender<T>) => void | PromiseLike<void>,
+  f: (send: Sender<T>) => void | PromiseLike<void>
 ): Receiver<T> {
   const { send, recv } = channel<T>();
   Promise.resolve(f(send)).then(noop).then(send.close, send.close);
@@ -143,3 +143,11 @@ export function semaphore(count = 1) {
 
   return acquire;
 }
+
+export function semaphore_fast() {
+  let last = Promise.resolve<unknown>(undefined);
+
+  return function acquire<T>(f: () => T | PromiseLike<T>) {
+    return (last = last.then(f, f));
+  };
+}
diff --git a/deno.json b/deno.json
index 6101a4a..6191a9c 100644
--- a/deno.json
+++ b/deno.json
@@ -1,5 +1,5 @@
 {
   "name": "@luaneko/lstd",
-  "version": "0.1.2",
+  "version": "0.1.3",
   "exports": "./mod.ts"
 }
diff --git a/events.ts b/events.ts
index 057a908..e0413dc 100644
--- a/events.ts
+++ b/events.ts
@@ -114,7 +114,7 @@ export class TypedEmitter<T extends EventMap> {
       b: any,
       c: any,
       d: any,
-      e: any,
+      e: any
     ) {
       const event = this.#events[name];
       if (!event) return false;
diff --git a/jit.ts b/jit.ts
index 7524e0c..394bc27 100644
--- a/jit.ts
+++ b/jit.ts
@@ -30,7 +30,7 @@ export class JitCompiler {
   compile() {
     return new Function(
       ...this.#args.values(),
-      `"use strict"; return (${this.#body});`,
+      `"use strict"; return (${this.#body});`
     )(...this.#args.keys());
   }
 }
@@ -99,7 +99,7 @@ export function literal(x: unknown) {
 export function map<T>(
   sep: string | JitFragment,
   xs: Iterable<T>,
-  f: (value: T, index: number) => unknown,
+  f: (value: T, index: number) => unknown
 ): JitFragment {
   return fragment(sep, ...Iterator.from(xs).map(f));
 }
@@ -107,7 +107,7 @@ export function map<T>(
 export function condition(
   test: unknown,
   consequent: JitFragment,
-  alternate: JitFragment = jit``,
+  alternate: JitFragment = jit``
 ): JitFragment {
   return test ? consequent : alternate;
 }