diff --git a/lib/index.js b/lib/index.js
index 6d1bb67..81a7681 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -82,7 +82,7 @@ AsyncLock.prototype.acquire = function(key, fn, cb, opts){
 
         if(locked){
         	//run next func
-	        if(!!self.queues[key]){
+	        if(!!self.queues[key] && self.queues[key].length > 0){
 	        	self.queues[key].shift()();
 	        }
         }