diff --git a/source/NetCoreServer/IWebSocket.cs b/source/NetCoreServer/IWebSocket.cs
index 0ea91e8..63f6181 100644
--- a/source/NetCoreServer/IWebSocket.cs
+++ b/source/NetCoreServer/IWebSocket.cs
@@ -53,7 +53,8 @@ void OnWsReceived(byte[] buffer, long offset, long size) {}
         /// <param name="buffer">Received buffer</param>
         /// <param name="offset">Received buffer offset</param>
         /// <param name="size">Received buffer size</param>
-        void OnWsClose(byte[] buffer, long offset, long size) {}
+        /// <param name="status">WebSocket close status (default is 1000)</param>
+        void OnWsClose(byte[] buffer, long offset, long size, int status = 1000) {}
 
         /// <summary>
         /// Handle WebSocket ping notification
diff --git a/source/NetCoreServer/NetCoreServer.csproj b/source/NetCoreServer/NetCoreServer.csproj
index bd978d8..27df22b 100644
--- a/source/NetCoreServer/NetCoreServer.csproj
+++ b/source/NetCoreServer/NetCoreServer.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
-    <Version>6.6.0.0</Version>
+    <Version>6.7.0.0</Version>
     <Authors>Ivan Shynkarenka</Authors>
     <Copyright>Copyright (c) 2019-2022 Ivan Shynkarenka</Copyright>
     <RepositoryUrl>https://github.com/chronoxor/NetCoreServer</RepositoryUrl>
diff --git a/source/NetCoreServer/UdpClient.cs b/source/NetCoreServer/UdpClient.cs
index 76f8365..e982277 100644
--- a/source/NetCoreServer/UdpClient.cs
+++ b/source/NetCoreServer/UdpClient.cs
@@ -457,7 +457,7 @@ public virtual long Send(EndPoint endpoint, ReadOnlySpan<byte> buffer)
             try
             {
                 // Sent datagram to the server
-                int sent = Socket.SendTo(buffer, SocketFlags.None, endpoint);
+                long sent = Socket.SendTo(buffer, SocketFlags.None, endpoint);
                 if (sent > 0)
                 {
                     // Update statistic
@@ -632,7 +632,7 @@ public virtual long Receive(ref EndPoint endpoint, byte[] buffer, long offset, l
             try
             {
                 // Receive datagram from the server
-                int received = Socket.ReceiveFrom(buffer, (int)offset, (int)size, SocketFlags.None, ref endpoint);
+                long received = Socket.ReceiveFrom(buffer, (int)offset, (int)size, SocketFlags.None, ref endpoint);
 
                 // Update statistic
                 DatagramsReceived++;
diff --git a/source/NetCoreServer/UdpServer.cs b/source/NetCoreServer/UdpServer.cs
index 250ed5b..13cd1eb 100644
--- a/source/NetCoreServer/UdpServer.cs
+++ b/source/NetCoreServer/UdpServer.cs
@@ -473,7 +473,7 @@ public virtual long Send(EndPoint endpoint, ReadOnlySpan<byte> buffer)
             try
             {
                 // Sent datagram to the client
-                int sent = Socket.SendTo(buffer, SocketFlags.None, endpoint);
+                long sent = Socket.SendTo(buffer, SocketFlags.None, endpoint);
                 if (sent > 0)
                 {
                     // Update statistic
@@ -610,7 +610,7 @@ public virtual long Receive(ref EndPoint endpoint, byte[] buffer, long offset, l
             try
             {
                 // Receive datagram from the client
-                int received = Socket.ReceiveFrom(buffer, (int)offset, (int)size, SocketFlags.None, ref endpoint);
+                long received = Socket.ReceiveFrom(buffer, (int)offset, (int)size, SocketFlags.None, ref endpoint);
 
                 // Update statistic
                 DatagramsReceived++;
diff --git a/source/NetCoreServer/WebSocket.cs b/source/NetCoreServer/WebSocket.cs
index 75d2d73..e33f43e 100644
--- a/source/NetCoreServer/WebSocket.cs
+++ b/source/NetCoreServer/WebSocket.cs
@@ -253,7 +253,7 @@ public bool PerformServerUpgrade(HttpRequest request, HttpResponse response)
         /// <param name="status">WebSocket status (default is 0)</param>
         public void PrepareSendFrame(byte opcode, bool mask, ReadOnlySpan<byte> buffer, int status = 0)
         {
-            int size = buffer.Length;
+            long size = (((opcode & WS_CLOSE) == WS_CLOSE) && (buffer.Length > 0)) ? (buffer.Length + 2) : buffer.Length;
 
             // Clear the previous WebSocket send buffer
             WsSendBuffer.Clear();
@@ -263,7 +263,7 @@ public void PrepareSendFrame(byte opcode, bool mask, ReadOnlySpan<byte> buffer,
 
             // Append WebSocket frame size
             if (size <= 125)
-                WsSendBuffer.Append((byte)((size & 0xFF) | (mask ? 0x80 : 0)));
+                WsSendBuffer.Append((byte)(((int)size & 0xFF) | (mask ? 0x80 : 0)));
             else if (size <= 65535)
             {
                 WsSendBuffer.Append((byte)(126 | (mask ? 0x80 : 0)));
@@ -284,11 +284,21 @@ public void PrepareSendFrame(byte opcode, bool mask, ReadOnlySpan<byte> buffer,
             }
 
             // Resize WebSocket frame buffer
-            int offset = (int)WsSendBuffer.Size;
+            long offset = WsSendBuffer.Size;
             WsSendBuffer.Resize(WsSendBuffer.Size + size);
 
+            int index = 0;
+
+            // Append WebSocket close status
+            if (((opcode & WS_CLOSE) == WS_CLOSE) && (buffer.Length > 0))
+            {
+                index += 2;
+                WsSendBuffer.Append((byte)((status >> 8) & 0xFF));
+                WsSendBuffer.Append((byte)(status & 0xFF));
+            }
+
             // Mask WebSocket frame content
-            for (int i = 0; i < size; i++)
+            for (int i = index; i < size; i++)
                 WsSendBuffer.Data[offset + i] = (byte)(buffer[i] ^ WsSendMask[i % 4]);
         }
 
@@ -302,7 +312,7 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
         {
             lock (WsReceiveLock)
             {
-                var index = 0;
+                int index = 0;
 
                 // Clear received data after WebSocket frame was processed
                 if (WsFrameReceived)
@@ -339,7 +349,7 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                     // Prepare WebSocket frame opcode and mask flag
                     if (WsReceiveFrameBuffer.Size < 2)
                     {
-                        for (int i = 0; i < 2; i++, index++, size--)
+                        for (long i = 0; i < 2; i++, index++, size--)
                         {
                             if (size == 0)
                                 return;
@@ -350,7 +360,7 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                     byte opcode = (byte)(WsReceiveFrameBuffer[0] & 0x0F);
                     bool fin = ((WsReceiveFrameBuffer[0] >> 7) & 0x01) != 0;
                     bool mask = ((WsReceiveFrameBuffer[1] >> 7) & 0x01) != 0;
-                    int payload = WsReceiveFrameBuffer[1] & (~0x80);
+                    long payload = WsReceiveFrameBuffer[1] & (~0x80);
 
                     // Prepare WebSocket opcode
                     WsOpcode = (opcode != 0) ? opcode : WsOpcode;
@@ -365,7 +375,7 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                     {
                         if (WsReceiveFrameBuffer.Size < 4)
                         {
-                            for (int i = 0; i < 2; i++, index++, size--)
+                            for (long i = 0; i < 2; i++, index++, size--)
                             {
                                 if (size == 0)
                                     return;
@@ -381,7 +391,7 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                     {
                         if (WsReceiveFrameBuffer.Size < 10)
                         {
-                            for (int i = 0; i < 8; i++, index++, size--)
+                            for (long i = 0; i < 8; i++, index++, size--)
                             {
                                 if (size == 0)
                                     return;
@@ -399,7 +409,7 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                     {
                         if (WsReceiveFrameBuffer.Size < WsHeaderSize)
                         {
-                            for (int i = 0; i < 4; i++, index++, size--)
+                            for (long i = 0; i < 4; i++, index++, size--)
                             {
                                 if (size == 0)
                                     return;
@@ -409,12 +419,12 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                         }
                     }
 
-                    int total = WsHeaderSize + WsPayloadSize;
-                    int length = Math.Min(total - (int)WsReceiveFrameBuffer.Size, (int)size);
+                    long total = WsHeaderSize + WsPayloadSize;
+                    long length = Math.Min(total - WsReceiveFrameBuffer.Size, size);
 
                     // Prepare WebSocket frame payload
-                    WsReceiveFrameBuffer.Append(buffer[((int)offset + index)..((int)offset + index + length)]);
-                    index += length;
+                    WsReceiveFrameBuffer.Append(buffer[((int)offset + index)..((int)offset + index + (int)length)]);
+                    index += (int)length;
                     size -= length;
 
                     // Process WebSocket frame
@@ -423,11 +433,11 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                         // Unmask WebSocket frame content
                         if (mask)
                         {
-                            for (int i = 0; i < WsPayloadSize; i++)
+                            for (long i = 0; i < WsPayloadSize; i++)
                                 WsReceiveFinalBuffer.Append((byte)(WsReceiveFrameBuffer[WsHeaderSize + i] ^ WsReceiveMask[i % 4]));
                         }
                         else
-                            WsReceiveFinalBuffer.Append(WsReceiveFrameBuffer.AsSpan().Slice(WsHeaderSize, WsPayloadSize));
+                            WsReceiveFinalBuffer.Append(WsReceiveFrameBuffer.AsSpan().Slice((int)WsHeaderSize, (int)WsPayloadSize));
 
                         WsFrameReceived = true;
 
@@ -452,8 +462,18 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                                 }
                                 case WS_CLOSE:
                                 {
+                                    int sindex = 0;
+                                    int status = 1000;
+
+                                    // Read WebSocket close status
+                                    if (WsReceiveFinalBuffer.Size > 2)
+                                    {
+                                        sindex += 2;
+                                        status = ((WsReceiveFinalBuffer[0] << 8) | (WsReceiveFinalBuffer[1] << 0));
+                                    }
+
                                     // Call the WebSocket close handler
-                                    _wsHandler.OnWsClose(WsReceiveFinalBuffer.Data, 0, WsReceiveFinalBuffer.Size);
+                                    _wsHandler.OnWsClose(WsReceiveFinalBuffer.Data, sindex, WsReceiveFinalBuffer.Size - sindex, status);
                                     break;
                                 }
                                 case WS_BINARY:
@@ -473,7 +493,7 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
         /// <summary>
         /// Required WebSocket receive frame size
         /// </summary>
-        public int RequiredReceiveFrameSize()
+        public long RequiredReceiveFrameSize()
         {
             lock (WsReceiveLock)
             {
@@ -482,23 +502,23 @@ public int RequiredReceiveFrameSize()
 
                 // Required WebSocket frame opcode and mask flag
                 if (WsReceiveFrameBuffer.Size < 2)
-                    return 2 - (int)WsReceiveFrameBuffer.Size;
+                    return 2 - WsReceiveFrameBuffer.Size;
 
                 bool mask = ((WsReceiveFrameBuffer[1] >> 7) & 0x01) != 0;
-                int payload = WsReceiveFrameBuffer[1] & (~0x80);
+                long payload = WsReceiveFrameBuffer[1] & (~0x80);
 
                 // Required WebSocket frame size
                 if ((payload == 126) && (WsReceiveFrameBuffer.Size < 4))
-                    return 4 - (int)WsReceiveFrameBuffer.Size;
+                    return 4 - WsReceiveFrameBuffer.Size;
                 if ((payload == 127) && (WsReceiveFrameBuffer.Size < 10))
-                    return 10 - (int)WsReceiveFrameBuffer.Size;
+                    return 10 - WsReceiveFrameBuffer.Size;
 
                 // Required WebSocket frame mask
                 if ((mask) && (WsReceiveFrameBuffer.Size < WsHeaderSize))
-                    return WsHeaderSize - (int)WsReceiveFrameBuffer.Size;
+                    return WsHeaderSize - WsReceiveFrameBuffer.Size;
 
                 // Required WebSocket frame payload
-                return WsHeaderSize + WsPayloadSize - (int)WsReceiveFrameBuffer.Size;
+                return WsHeaderSize + WsPayloadSize - WsReceiveFrameBuffer.Size;
             }
         }
 
@@ -561,15 +581,15 @@ public void ClearWsBuffers()
         /// <summary>
         /// Received frame opcode
         /// </summary>
-        internal int WsOpcode;
+        internal byte WsOpcode;
         /// <summary>
         /// Received frame header size
         /// </summary>
-        internal int WsHeaderSize;
+        internal long WsHeaderSize;
         /// <summary>
         /// Received frame payload size
         /// </summary>
-        internal int WsPayloadSize;
+        internal long WsPayloadSize;
 
         /// <summary>
         /// Receive buffer lock
diff --git a/source/NetCoreServer/WsClient.cs b/source/NetCoreServer/WsClient.cs
index 46fa9e7..ce7bbb7 100644
--- a/source/NetCoreServer/WsClient.cs
+++ b/source/NetCoreServer/WsClient.cs
@@ -220,9 +220,9 @@ public string ReceiveText()
             {
                 while (!WebSocket.WsFrameReceived)
                 {
-                    int required = WebSocket.RequiredReceiveFrameSize();
+                    long required = WebSocket.RequiredReceiveFrameSize();
                     cache.Resize(required);
-                    int received = (int)base.Receive(cache.Data, 0, required);
+                    long received = base.Receive(cache.Data, 0, required);
                     if (received != required)
                         return result.ExtractString(0, result.Data.Length);
                     WebSocket.PrepareReceiveFrame(cache.Data, 0, received);
@@ -251,9 +251,9 @@ public Buffer ReceiveBinary()
             {
                 while (!WebSocket.WsFrameReceived)
                 {
-                    int required = WebSocket.RequiredReceiveFrameSize();
+                    long required = WebSocket.RequiredReceiveFrameSize();
                     cache.Resize(required);
-                    int received = (int)base.Receive(cache.Data, 0, required);
+                    long received = base.Receive(cache.Data, 0, required);
                     if (received != required)
                         return result;
                     WebSocket.PrepareReceiveFrame(cache.Data, 0, received);
@@ -378,7 +378,7 @@ public virtual void OnWsConnected(HttpRequest request) {}
         public virtual void OnWsDisconnecting() {}
         public virtual void OnWsDisconnected() {}
         public virtual void OnWsReceived(byte[] buffer, long offset, long size) {}
-        public virtual void OnWsClose(byte[] buffer, long offset, long size) { CloseAsync(1000); }
+        public virtual void OnWsClose(byte[] buffer, long offset, long size, int status = 1000) { CloseAsync(status); }
         public virtual void OnWsPing(byte[] buffer, long offset, long size) { SendPongAsync(buffer, offset, size); }
         public virtual void OnWsPong(byte[] buffer, long offset, long size) {}
         public virtual void OnWsError(string error) { OnError(SocketError.SocketError); }
diff --git a/source/NetCoreServer/WsSession.cs b/source/NetCoreServer/WsSession.cs
index 2296244..a81f4ab 100644
--- a/source/NetCoreServer/WsSession.cs
+++ b/source/NetCoreServer/WsSession.cs
@@ -187,9 +187,9 @@ public string ReceiveText()
             {
                 while (!WebSocket.WsFrameReceived)
                 {
-                    int required = WebSocket.RequiredReceiveFrameSize();
+                    long required = WebSocket.RequiredReceiveFrameSize();
                     cache.Resize(required);
-                    int received = (int)base.Receive(cache.Data, 0, required);
+                    long received = base.Receive(cache.Data, 0, required);
                     if (received != required)
                         return result.ExtractString(0, result.Data.Length);
                     WebSocket.PrepareReceiveFrame(cache.Data, 0, received);
@@ -218,9 +218,9 @@ public Buffer ReceiveBinary()
             {
                 while (!WebSocket.WsFrameReceived)
                 {
-                    int required = WebSocket.RequiredReceiveFrameSize();
+                    long required = WebSocket.RequiredReceiveFrameSize();
                     cache.Resize(required);
-                    int received = (int)base.Receive(cache.Data, 0, required);
+                    long received = base.Receive(cache.Data, 0, required);
                     if (received != required)
                         return result;
                     WebSocket.PrepareReceiveFrame(cache.Data, 0, received);
@@ -330,7 +330,7 @@ public virtual void OnWsConnected(HttpRequest request) {}
         public virtual void OnWsDisconnecting() {}
         public virtual void OnWsDisconnected() {}
         public virtual void OnWsReceived(byte[] buffer, long offset, long size) {}
-        public virtual void OnWsClose(byte[] buffer, long offset, long size) { Close(1000); }
+        public virtual void OnWsClose(byte[] buffer, long offset, long size, int status = 1000) { Close(status); }
         public virtual void OnWsPing(byte[] buffer, long offset, long size) { SendPongAsync(buffer, offset, size); }
         public virtual void OnWsPong(byte[] buffer, long offset, long size) {}
         public virtual void OnWsError(string error) { OnError(SocketError.SocketError); }
diff --git a/source/NetCoreServer/WssClient.cs b/source/NetCoreServer/WssClient.cs
index bc4906b..263b412 100644
--- a/source/NetCoreServer/WssClient.cs
+++ b/source/NetCoreServer/WssClient.cs
@@ -224,9 +224,9 @@ public string ReceiveText()
             {
                 while (!WebSocket.WsFrameReceived)
                 {
-                    int required = WebSocket.RequiredReceiveFrameSize();
+                    long required = WebSocket.RequiredReceiveFrameSize();
                     cache.Resize(required);
-                    int received = (int)base.Receive(cache.Data, 0, required);
+                    long received = (int)base.Receive(cache.Data, 0, required);
                     if (received != required)
                         return result.ExtractString(0, result.Data.Length);
                     WebSocket.PrepareReceiveFrame(cache.Data, 0, received);
@@ -255,9 +255,9 @@ public Buffer ReceiveBinary()
             {
                 while (!WebSocket.WsFrameReceived)
                 {
-                    int required = WebSocket.RequiredReceiveFrameSize();
+                    long required = WebSocket.RequiredReceiveFrameSize();
                     cache.Resize(required);
-                    int received = (int)base.Receive(cache.Data, 0, required);
+                    long received = (int)base.Receive(cache.Data, 0, required);
                     if (received != required)
                         return result;
                     WebSocket.PrepareReceiveFrame(cache.Data, 0, received);
@@ -382,7 +382,7 @@ public virtual void OnWsConnected(HttpRequest request) {}
         public virtual void OnWsDisconnecting() {}
         public virtual void OnWsDisconnected() {}
         public virtual void OnWsReceived(byte[] buffer, long offset, long size) {}
-        public virtual void OnWsClose(byte[] buffer, long offset, long size) { CloseAsync(1000); }
+        public virtual void OnWsClose(byte[] buffer, long offset, long size, int status = 1000) { CloseAsync(status); }
         public virtual void OnWsPing(byte[] buffer, long offset, long size) { SendPongAsync(buffer, offset, size); }
         public virtual void OnWsPong(byte[] buffer, long offset, long size) {}
         public virtual void OnWsError(string error) { OnError(SocketError.SocketError); }
diff --git a/source/NetCoreServer/WssSession.cs b/source/NetCoreServer/WssSession.cs
index c0fb4da..7553d0b 100644
--- a/source/NetCoreServer/WssSession.cs
+++ b/source/NetCoreServer/WssSession.cs
@@ -187,9 +187,9 @@ public string ReceiveText()
             {
                 while (!WebSocket.WsFrameReceived)
                 {
-                    int required = WebSocket.RequiredReceiveFrameSize();
+                    long required = WebSocket.RequiredReceiveFrameSize();
                     cache.Resize(required);
-                    int received = (int)base.Receive(cache.Data, 0, required);
+                    long received = base.Receive(cache.Data, 0, required);
                     if (received != required)
                         return result.ExtractString(0, result.Data.Length);
                     WebSocket.PrepareReceiveFrame(cache.Data, 0, received);
@@ -218,9 +218,9 @@ public Buffer ReceiveBinary()
             {
                 while (!WebSocket.WsFrameReceived)
                 {
-                    int required = WebSocket.RequiredReceiveFrameSize();
+                    long required = WebSocket.RequiredReceiveFrameSize();
                     cache.Resize(required);
-                    int received = (int)base.Receive(cache.Data, 0, required);
+                    long received = base.Receive(cache.Data, 0, required);
                     if (received != required)
                         return result;
                     WebSocket.PrepareReceiveFrame(cache.Data, 0, received);
@@ -330,7 +330,7 @@ public virtual void OnWsConnected(HttpRequest request) {}
         public virtual void OnWsDisconnecting() {}
         public virtual void OnWsDisconnected() {}
         public virtual void OnWsReceived(byte[] buffer, long offset, long size) {}
-        public virtual void OnWsClose(byte[] buffer, long offset, long size) { Close(1000); }
+        public virtual void OnWsClose(byte[] buffer, long offset, long size, int status = 1000) { Close(status); }
         public virtual void OnWsPing(byte[] buffer, long offset, long size) { SendPongAsync(buffer, offset, size); }
         public virtual void OnWsPong(byte[] buffer, long offset, long size) {}
         public virtual void OnWsError(string error) { OnError(SocketError.SocketError); }