diff --git a/watchtower/wtwire/fuzz_test.go b/watchtower/wtwire/fuzz_test.go
index 5a03b84e3e..385e5a58bf 100644
--- a/watchtower/wtwire/fuzz_test.go
+++ b/watchtower/wtwire/fuzz_test.go
@@ -18,25 +18,28 @@ func prefixWithMsgType(data []byte, prefix MessageType) []byte {
 	return data
 }
 
-// harness performs the actual fuzz testing of the appropriate wire message.
-// This function will check that the passed-in message passes wire length
-// checks, is a valid message once deserialized, and passes a sequence of
-// serialization and deserialization checks. Returns an int that determines
-// whether the input is unique or not.
-func harness(t *testing.T, data []byte, emptyMsg Message) {
+// wireMsgHarness performs the actual fuzz testing of the appropriate wire
+// message. This function will check that the passed-in message passes wire
+// length checks, is a valid message once deserialized, and passes a sequence of
+// serialization and deserialization checks. emptyMsg must be an empty Message
+// of the type to be fuzzed, as it is used to determine the appropriate prefix
+// bytes and max payload length for decoding.
+func wireMsgHarness(t *testing.T, data []byte, emptyMsg Message) {
 	t.Helper()
 
-	// Create a reader with the byte array.
-	r := bytes.NewReader(data)
-
-	// Make sure byte array length (excluding 2 bytes for message type) is
-	// less than max payload size for the wire message.
-	payloadLen := uint32(len(data)) - 2
+	// Make sure byte array length is less than max payload size for the
+	// wire message.
+	payloadLen := uint32(len(data))
 	if payloadLen > emptyMsg.MaxPayloadLength(0) {
 		// Ignore this input - max payload constraint violated.
 		return
 	}
 
+	data = prefixWithMsgType(data, emptyMsg.MsgType())
+
+	// Create a reader with the byte array.
+	r := bytes.NewReader(data)
+
 	msg, err := ReadMessage(r, 0)
 	if err != nil {
 		return
@@ -57,120 +60,48 @@ func harness(t *testing.T, data []byte, emptyMsg Message) {
 
 func FuzzCreateSessionReply(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
-		// Prefix with MsgCreateSessionReply.
-		data = prefixWithMsgType(data, MsgCreateSessionReply)
-
-		// Create an empty message so that the FuzzHarness func can
-		// check if the max payload constraint is violated.
-		emptyMsg := CreateSessionReply{}
-
-		// Pass the message into our general fuzz harness for wire
-		// messages!
-		harness(t, data, &emptyMsg)
+		wireMsgHarness(t, data, &CreateSessionReply{})
 	})
 }
 
 func FuzzCreateSession(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
-		// Prefix with MsgCreateSession.
-		data = prefixWithMsgType(data, MsgCreateSession)
-
-		// Create an empty message so that the FuzzHarness func can
-		// check if the max payload constraint is violated.
-		emptyMsg := CreateSession{}
-
-		// Pass the message into our general fuzz harness for wire
-		// messages!
-		harness(t, data, &emptyMsg)
+		wireMsgHarness(t, data, &CreateSession{})
 	})
 }
 
 func FuzzDeleteSessionReply(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
-		// Prefix with MsgDeleteSessionReply.
-		data = prefixWithMsgType(data, MsgDeleteSessionReply)
-
-		// Create an empty message so that the FuzzHarness func can
-		// check if the max payload constraint is violated.
-		emptyMsg := DeleteSessionReply{}
-
-		// Pass the message into our general fuzz harness for wire
-		// messages!
-		harness(t, data, &emptyMsg)
+		wireMsgHarness(t, data, &DeleteSessionReply{})
 	})
 }
 
 func FuzzDeleteSession(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
-		// Prefix with MsgDeleteSession.
-		data = prefixWithMsgType(data, MsgDeleteSession)
-
-		// Create an empty message so that the FuzzHarness func can
-		// check if the max payload constraint is violated.
-		emptyMsg := DeleteSession{}
-
-		// Pass the message into our general fuzz harness for wire
-		// messages!
-		harness(t, data, &emptyMsg)
+		wireMsgHarness(t, data, &DeleteSession{})
 	})
 }
 
 func FuzzError(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
-		// Prefix with MsgError.
-		data = prefixWithMsgType(data, MsgError)
-
-		// Create an empty message so that the FuzzHarness func can
-		// check if the max payload constraint is violated.
-		emptyMsg := Error{}
-
-		// Pass the message into our general fuzz harness for wire
-		// messages!
-		harness(t, data, &emptyMsg)
+		wireMsgHarness(t, data, &Error{})
 	})
 }
 
 func FuzzInit(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
-		// Prefix with MsgInit.
-		data = prefixWithMsgType(data, MsgInit)
-
-		// Create an empty message so that the FuzzHarness func can
-		// check if the max payload constraint is violated.
-		emptyMsg := Init{}
-
-		// Pass the message into our general fuzz harness for wire
-		// messages!
-		harness(t, data, &emptyMsg)
+		wireMsgHarness(t, data, &Init{})
 	})
 }
 
 func FuzzStateUpdateReply(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
-		// Prefix with MsgStateUpdateReply.
-		data = prefixWithMsgType(data, MsgStateUpdateReply)
-
-		// Create an empty message so that the FuzzHarness func can
-		// check if the max payload constraint is violated.
-		emptyMsg := StateUpdateReply{}
-
-		// Pass the message into our general fuzz harness for wire
-		// messages!
-		harness(t, data, &emptyMsg)
+		wireMsgHarness(t, data, &StateUpdateReply{})
 	})
 }
 
 func FuzzStateUpdate(f *testing.F) {
 	f.Fuzz(func(t *testing.T, data []byte) {
-		// Prefix with MsgStateUpdate.
-		data = prefixWithMsgType(data, MsgStateUpdate)
-
-		// Create an empty message so that the FuzzHarness func can
-		// check if the max payload constraint is violated.
-		emptyMsg := StateUpdate{}
-
-		// Pass the message into our general fuzz harness for wire
-		// messages!
-		harness(t, data, &emptyMsg)
+		wireMsgHarness(t, data, &StateUpdate{})
 	})
 }