diff --git a/source/Runtime/Common/MessageProcessor.cs b/source/Runtime/Common/MessageProcessor.cs
index 0d3d766..d5fb48f 100644
--- a/source/Runtime/Common/MessageProcessor.cs
+++ b/source/Runtime/Common/MessageProcessor.cs
@@ -4,6 +4,14 @@
 
 namespace JamesFrowen.SimpleWeb
 {
+    public enum OpCode : byte
+    {
+        continuation = 0,
+        text = 1,
+        binary = 2,
+        close = 8,
+    }
+
     public static class MessageProcessor
     {
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -25,9 +33,9 @@ public static bool NeedToReadLongLength(byte[] buffer)
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static int GetOpcode(byte[] buffer)
+        public static OpCode GetOpcode(byte[] buffer)
         {
-            return buffer[0] & 0b0000_1111;
+            return (OpCode)(buffer[0] & 0b0000_1111);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -53,7 +61,7 @@ public static void ValidateHeader(byte[] buffer, int maxLength, bool expectMask,
             bool finished = Finished(buffer);
             bool hasMask = (buffer[1] & 0b1000_0000) != 0; // true from clients, false from server, "All messages from the client to the server have this bit set"
 
-            int opcode = buffer[0] & 0b0000_1111; // expecting 1 - text message
+            OpCode opcode = GetOpcode(buffer);
             byte lenByte = FirstLengthByte(buffer);
 
             ThrowIfMaskNotExpected(hasMask, expectMask);
@@ -136,34 +144,29 @@ static void ThrowIfMaskNotExpected(bool hasMask, bool expectMask)
         }
 
         /// <exception cref="InvalidDataException"></exception>
-        static void ThrowIfBadOpCode(int opcode, bool finished, bool opCodeContinuation)
+        static void ThrowIfBadOpCode(OpCode opcode, bool finished, bool opCodeContinuation)
         {
-            // 0 = continuation
-            // 2 = binary
-            // 8 = close
-
             // do we expect Continuation?
             if (opCodeContinuation)
             {
                 // good it was Continuation
-                if (opcode == 0)
+                if (opcode == OpCode.continuation)
                     return;
 
-                // bad, wasn't Continuation
                 throw new InvalidDataException("Expected opcode to be Continuation");
             }
             else if (!finished)
             {
-                // fragmented message, should be binary
-                if (opcode == 2)
+                // Fragmented message, should be binary
+                if (opcode == OpCode.binary)
                     return;
 
                 throw new InvalidDataException("Expected opcode to be binary");
             }
             else
             {
-                // normal message, should be binary or close
-                if (opcode == 2 || opcode == 8)
+                // Normal message, should be binary, text, or close
+                if (opcode == OpCode.binary || opcode == OpCode.close)
                     return;
 
                 throw new InvalidDataException($"Unexpected opcode {opcode}");
diff --git a/source/Runtime/Common/ReceiveLoop.cs b/source/Runtime/Common/ReceiveLoop.cs
index 8768dd2..97dd8c2 100644
--- a/source/Runtime/Common/ReceiveLoop.cs
+++ b/source/Runtime/Common/ReceiveLoop.cs
@@ -42,7 +42,7 @@ struct Header
         {
             public int payloadLength;
             public int offset;
-            public int opcode;
+            public OpCode opcode;
             public bool finished;
         }
 
@@ -124,10 +124,10 @@ static void ReadOneMessage(Config config, byte[] buffer)
             {
                 switch (header.opcode)
                 {
-                    case 2:
+                    case OpCode.binary:
                         HandleArrayMessage(config, buffer, msgOffset, header.payloadLength);
                         break;
-                    case 8:
+                    case OpCode.close:
                         HandleCloseMessage(config, buffer, msgOffset, header.payloadLength);
                         break;
                 }