diff --git a/Source/SocketAckManager.swift b/Source/SocketAckManager.swift
index 8143243..e229c93 100644
--- a/Source/SocketAckManager.swift
+++ b/Source/SocketAckManager.swift
@@ -56,19 +56,17 @@ struct SocketAckManager {
         acks.insert(SocketAck(ack: ack, callback: callback))
     }
     
+    /// Should be called on handle queue
     mutating func executeAck(ack: Int, items: [AnyObject]) {
         let callback = acks.remove(SocketAck(ack: ack))
-
-        dispatch_async(dispatch_get_main_queue()) {
-            callback?.callback(items)
-        }
+        
+        callback?.callback(items)
     }
     
+    /// Should be called on handle queue
     mutating func timeoutAck(ack: Int) {
         let callback = acks.remove(SocketAck(ack: ack))
         
-        dispatch_async(dispatch_get_main_queue()) {
-            callback?.callback(["NO ACK"])
-        }
+        callback?.callback(["NO ACK"])
     }
 }
diff --git a/Source/SocketIOClient.swift b/Source/SocketIOClient.swift
index 70c6f22..a176059 100644
--- a/Source/SocketIOClient.swift
+++ b/Source/SocketIOClient.swift
@@ -60,6 +60,7 @@ public final class SocketIOClient : NSObject, SocketEngineClient, SocketParsable
     private var reconnecting = false
 
     private(set) var currentAck = -1
+    // Handle queue also controls access to ackManager
     private(set) var handleQueue = dispatch_get_main_queue()
     private(set) var reconnectAttempts = -1
 
@@ -162,7 +163,10 @@ public final class SocketIOClient : NSObject, SocketEngineClient, SocketParsable
 
         return {[weak self, ack = currentAck] timeout, callback in
             if let this = self {
-                this.ackHandlers.addAck(ack, callback: callback)
+                dispatch_sync(this.handleQueue) {
+                    this.ackHandlers.addAck(ack, callback: callback)
+                }
+                
                 this._emit(items, ack: ack)
 
                 if timeout != 0 {
@@ -294,7 +298,9 @@ public final class SocketIOClient : NSObject, SocketEngineClient, SocketParsable
 
         DefaultSocketLogger.Logger.log("Handling ack: %@ with data: %@", type: logType, args: ack, data ?? "")
 
-        ackHandlers.executeAck(ack, items: data)
+        dispatch_async(handleQueue) {
+            self.ackHandlers.executeAck(ack, items: data)
+        }
     }
 
     /// Causes an event to be handled. Only use if you know what you're doing.