From ab4157db601f36f433305da865ef891f48d95e52 Mon Sep 17 00:00:00 2001
From: Graeme Yeates <yeatesgraeme@gmail.com>
Date: Thu, 2 Jul 2015 17:55:00 -0400
Subject: [PATCH] once: ensure fn is gced

---
 lib/async.js | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/async.js b/lib/async.js
index 67eb379eb..342dcda05 100644
--- a/lib/async.js
+++ b/lib/async.js
@@ -30,20 +30,18 @@
     };
 
     function only_once(fn) {
-        var called = false;
         return function() {
-            if (called) throw new Error("Callback was already called.");
-            called = true;
+            if (fn === null) throw new Error("Callback was already called.");
             fn.apply(this, arguments);
+            fn = null;
         };
     }
 
     function _once(fn) {
-        var called = false;
         return function() {
-            if (called) return;
-            called = true;
+            if (fn === null) return;
             fn.apply(this, arguments);
+            fn = null;
         };
     }