diff --git a/Unity3D/ConcurrentDictionary.cs b/Unity3D/ConcurrentDictionary.cs
index 508ec95..ebb18bf 100644
--- a/Unity3D/ConcurrentDictionary.cs
+++ b/Unity3D/ConcurrentDictionary.cs
@@ -1,4 +1,4 @@
-#if !UNITY_WSA
+#if !UNITY_5_6_OR_NEWER || NET_2_0 || NET_2_0_SUBSET
 using System;
 using System.Collections;
 using System.Collections.Generic;
@@ -8,7 +8,7 @@
 using System.Runtime.Serialization;
 using System.Threading;
 
-namespace TcpServer
+namespace System.Collections.Concurrent
 {
 
     /// <summary>
diff --git a/Unity3D/PocoManager.cs b/Unity3D/PocoManager.cs
index c2c46f8..467c059 100644
--- a/Unity3D/PocoManager.cs
+++ b/Unity3D/PocoManager.cs
@@ -2,6 +2,7 @@
 using Newtonsoft.Json.Linq;
 using Poco;
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
diff --git a/Unity3D/TcpServer.cs b/Unity3D/TcpServer.cs
index ed06c63..36bec37 100644
--- a/Unity3D/TcpServer.cs
+++ b/Unity3D/TcpServer.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Threading;
 using System.Collections;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
 using System.Net;