diff --git a/Source/MQTTnet/Formatter/V5/MqttV5PacketDecoder.cs b/Source/MQTTnet/Formatter/V5/MqttV5PacketDecoder.cs
index c9010cab..e27f129f 100644
--- a/Source/MQTTnet/Formatter/V5/MqttV5PacketDecoder.cs
+++ b/Source/MQTTnet/Formatter/V5/MqttV5PacketDecoder.cs
@@ -68,12 +68,12 @@ public MqttPacket Decode(ReceivedMqttPacket receivedMqttPacket)
 
         MqttPacket DecodeAuthPacket(ArraySegment<byte> body)
         {
-            ThrowIfBodyIsEmpty(body);
-
             _bufferReader.SetBuffer(body.Array, body.Offset, body.Count);
 
             var packet = new MqttAuthPacket();
 
+            // MQTT spec: The Reason Code and Property Length can be omitted if the Reason Code is 0x00 (Success) and there are no Properties.
+            // In this case the AUTH has a Remaining Length of 0.
             if (_bufferReader.EndOfStream)
             {
                 packet.ReasonCode = MqttAuthenticateReasonCode.Success;
diff --git a/Source/MQTTnet/Formatter/V5/MqttV5PacketEncoder.cs b/Source/MQTTnet/Formatter/V5/MqttV5PacketEncoder.cs
index 74232e87..06863fa0 100644
--- a/Source/MQTTnet/Formatter/V5/MqttV5PacketEncoder.cs
+++ b/Source/MQTTnet/Formatter/V5/MqttV5PacketEncoder.cs
@@ -67,6 +67,13 @@ public MqttPacketBuffer Encode(MqttPacket packet)
 
     byte EncodeAuthPacket(MqttAuthPacket packet)
     {
+        // MQTT spec: The Reason Code and Property Length can be omitted if the Reason Code is 0x00 (Success) and there are no Properties.
+        // In this case the AUTH has a Remaining Length of 0.
+        if (packet.ReasonCode == MqttAuthenticateReasonCode.Success && _propertiesWriter.Length == 0)
+        {
+            return MqttBufferWriter.BuildFixedHeader(MqttControlPacketType.Auth);
+        }
+
         _bufferWriter.WriteByte((byte)packet.ReasonCode);
 
         _propertiesWriter.WriteAuthenticationMethod(packet.AuthenticationMethod);