diff --git a/hk_test.go b/hk_test.go
new file mode 100644
index 0000000..04911aa
--- /dev/null
+++ b/hk_test.go
@@ -0,0 +1,179 @@
+// hk_test is a start at a decoder I was writing, which exhibited some problems.
+// It also illustrates what a real decoder might look like.
+
+package netshovel
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"strings"
+	"sync"
+	"testing"
+
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/tcpassembly"
+)
+
+var wg sync.WaitGroup
+
+// HKStreamFactory generates HKStreams.
+type HKStreamFactory struct {
+	err *error
+}
+
+// New returns a new HKStream.
+func (f *HKStreamFactory) New(net, transport gopacket.Flow) tcpassembly.Stream {
+	stream := &HKStream{
+		Stream: NewStream(net, transport),
+		err:    f.err,
+	}
+	wg.Add(1)
+	go stream.Decode(&wg)
+
+	return stream
+}
+
+// HKStream represents half of a TCP Stream.
+type HKStream struct {
+	*Stream
+	err *error
+}
+
+func (stream HKStream) Read(length int) (Utterance, error) {
+	u, err := stream.Stream.Read(length)
+	return u, err
+}
+
+// DisplayUtterance prints an unparsed TCP utterance
+func (stream HKStream) DisplayUtterance(u Utterance) {
+	fmt.Printf("Unparsed %v:%v → %v:%v\n",
+		stream.Net.Src().String(), stream.Transport.Src().String(),
+		stream.Net.Dst().String(), stream.Transport.Dst().String(),
+	)
+	fmt.Println(u.Data.Hexdump())
+}
+
+// Display prints as much about an HKPacket as we are able to determine.
+func (stream HKStream) Display(pkt HKPacket) {
+	out := new(strings.Builder)
+
+	fmt.Fprintf(out, "HK %v:%v → %v:%v\n",
+		stream.Net.Src().String(), stream.Transport.Src().String(),
+		stream.Net.Dst().String(), stream.Transport.Dst().String(),
+	)
+	out.WriteString(pkt.Describe())
+	fmt.Println(out.String())
+}
+
+// Decode decodes all data from the stream.
+func (stream HKStream) Decode(wg *sync.WaitGroup) {
+	defer wg.Done()
+	for {
+		utterance, err := stream.Read(2)
+		if err == io.EOF {
+			return
+		} else if err != nil {
+			log.Println(err)
+			return
+		}
+
+		// Was it actually HK?
+		if utterance.Data.String("DROP") != "HK" {
+			u, err := stream.Read(-1)
+			if err != nil {
+				log.Println(err)
+				return
+			}
+
+			if utterance.When != u.When {
+				stream.DisplayUtterance(utterance)
+				utterance = u
+				*stream.err = fmt.Errorf("Short length on non-HK packet, and a different utterance was returned")
+			} else {
+				utterance.Data = utterance.Data.Append(u.Data)
+			}
+			if utterance.Data.Length() < 10 {
+				*stream.err = fmt.Errorf("Short length on non-HK packet")
+				return
+			}
+			stream.DisplayUtterance(utterance)
+			continue
+		}
+
+		pkt := NewHKPacket(utterance)
+		if err := pkt.Decode(stream); err != nil {
+			log.Println(err)
+			return
+		}
+		stream.Display(pkt)
+	}
+}
+
+// NewHKPacket returns a shiny new HKPacket.
+func NewHKPacket(u Utterance) HKPacket {
+	pkt := HKPacket{
+		Packet: NewPacket(),
+	}
+	pkt.Payload = u.Data
+	pkt.When = u.When
+	return pkt
+}
+
+// HKPacket is a single HK packet.
+type HKPacket struct {
+	Packet
+}
+
+// Decode from a readable
+func (pkt *HKPacket) Decode(stream HKStream) error {
+	header, err := stream.Read(9)
+	if err != nil {
+		return err
+	}
+	pkt.Payload = header.Data
+
+	unknown, _ := pkt.Uint32BE("unknown")
+	length, _ := pkt.Uint32BE("length")
+	opcode, _ := pkt.Uint8("opcode")
+	pkt.Opcode = int(opcode)
+
+	if unknown != 0 {
+		return fmt.Errorf("unknown header was actually %d", unknown)
+	}
+	if length > 100 {
+		return fmt.Errorf("Length too big: %d", length)
+	}
+
+	body, err := stream.Read(int(length - 9 - 2))
+	if err != nil {
+		return err
+	}
+	pkt.Payload = body.Data
+
+	subcode, _ := pkt.Uint8("subcode")
+	if subcode != 0 {
+		return fmt.Errorf("Subcode not zero: %d", subcode)
+	}
+	pkt.SetString("Payload", pkt.Payload.String("DROP"))
+
+	switch pkt.Opcode {
+	case 7:
+		pkt.Description = "Keepalive"
+	}
+
+	return nil
+}
+
+func TestHK(t *testing.T) {
+	factory := HKStreamFactory{err: new(error)}
+	streamPool := tcpassembly.NewStreamPool(&factory)
+	assembler := tcpassembly.NewAssembler(streamPool)
+	ShovelFile("testdata/hk.pcap", assembler)
+	assembler.FlushAll()
+	wg.Wait()
+
+	if *factory.err != nil {
+		t.Error(*factory.err)
+	}
+}
diff --git a/testdata/hk.pcap b/testdata/hk.pcap
new file mode 100644
index 0000000..8037518
Binary files /dev/null and b/testdata/hk.pcap differ