diff --git a/itch/5.0/stock_directory.go b/itch/5.0/stock_directory.go
index 628aec5..0aa5533 100644
--- a/itch/5.0/stock_directory.go
+++ b/itch/5.0/stock_directory.go
@@ -161,12 +161,12 @@ func (s StockDirectory) Bytes() []byte {
 	binary.BigEndian.PutUint64(data[3:11], uint64(s.Timestamp.Nanoseconds()))
 	binary.BigEndian.PutUint16(data[3:5], s.TrackingNumber)
 
-	copy(data[11:19], []byte(fmt.Sprintf("'%-8s'", s.Stock)))
+	copy(data[11:19], []byte(fmt.Sprintf("%-8s", s.Stock)))
 
 	data[19] = byte(s.MarketCategory)
 	data[20] = byte(s.FinancialStatusIndicator)
 
-	binary.BigEndian.AppendUint32(data[21:25], s.RoundLotSize)
+	binary.BigEndian.PutUint32(data[21:25], s.RoundLotSize)
 
 	if s.RoundLotsOnly {
 		data[25] = 'Y'
@@ -175,14 +175,12 @@ func (s StockDirectory) Bytes() []byte {
 	}
 
 	data[26] = byte(s.IssueClassification)
-	copy(data[27:29], []byte(s.IssueSubType))
+	underlying := string(s.IssueSubType)
+	copy(data[27:29], []byte(fmt.Sprintf("%-2s", underlying)))
 
-	if s.Authenticity == AUTHENTICITY_LIVE {
-		data[29] = 'P'
-	} else {
-		data[29] = 'T'
-	}
+	data[29] = byte(s.Authenticity)
 
+	// TODO: Make types
 	data[30] = []byte(s.ShortSaleThresholdIndicator)[0]
 	data[31] = []byte(s.IpoFlag)[0]
 	data[32] = []byte(s.LuldReferencePriceTier)[0]
@@ -204,6 +202,11 @@ func ParseStockDirectory(data []byte) (StockDirectory, error) {
 		return StockDirectory{}, NewInvalidPacketSize(stockDirectorySize, len(data))
 	}
 
+	for i := range len(data) {
+		fmt.Printf("%v,", data[i])
+	}
+	fmt.Println("")
+
 	locate := binary.BigEndian.Uint16(data[1:3])
 	tracking := binary.BigEndian.Uint16(data[3:5])
 	data[3] = 0
diff --git a/itch/5.0/stock_directory_test.go b/itch/5.0/stock_directory_test.go
new file mode 100644
index 0000000..07ef33f
--- /dev/null
+++ b/itch/5.0/stock_directory_test.go
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2022 Mark Edward Winter
+ */
+
+package itch
+
+import (
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestParseStockDirectory(t *testing.T) {
+	timestamp, _ := time.ParseDuration("3h7m14.939262551s")
+
+	type args struct {
+		data []byte
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    StockDirectory
+		wantErr bool
+	}{
+		{
+			name: "",
+			args: args{data: []byte{82, 3, 81, 0, 0, 10, 55, 214, 144, 86, 87, 66, 72, 66, 32, 32, 32, 32, 32, 65, 32, 0, 0, 0, 100, 78, 67, 90, 32, 80, 78, 32, 50, 78, 0, 0, 0, 0, 78}},
+			want: StockDirectory{
+				Timestamp:                   timestamp,
+				Stock:                       "BHB",
+				StockLocate:                 849,
+				TrackingNumber:              0,
+				RoundLotSize:                100,
+				RoundLotsOnly:               false,
+				IssueSubType:                ICS_NOT_APPLICABLE,
+				IssueClassification:         IC_COMMON_STOCK,
+				InverseIndicator:            false,
+				Authenticity:                AUTHENTICITY_LIVE,
+				EtpLeverageFactor:           0,
+				ShortSaleThresholdIndicator: "N",
+				IpoFlag:                     " ",
+				LuldReferencePriceTier:      "2",
+				EtpFlag:                     "N",
+				MarketCategory:              MKTCTG_NYSE_AMERICAN,
+				FinancialStatusIndicator:    FSI_NOT_AVAILABLE,
+			},
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ParseStockDirectory(tt.args.data)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseStockDirectory() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !cmp.Equal(got, tt.want) {
+				t.Errorf("%v", cmp.Diff(tt.want, got))
+			}
+		})
+	}
+}
+
+func TestStockDirectory_Bytes(t *testing.T) {
+	timestamp, _ := time.ParseDuration("3h7m14.939262551s")
+
+	tests := []struct {
+		name string
+		s    StockDirectory
+		want []byte
+	}{
+		{
+			name: "BHB",
+			s: StockDirectory{
+				Timestamp:                   timestamp,
+				Stock:                       "BHB",
+				StockLocate:                 849,
+				TrackingNumber:              0,
+				RoundLotSize:                100,
+				RoundLotsOnly:               false,
+				IssueSubType:                ICS_NOT_APPLICABLE,
+				IssueClassification:         IC_COMMON_STOCK,
+				InverseIndicator:            false,
+				Authenticity:                AUTHENTICITY_LIVE,
+				EtpLeverageFactor:           0,
+				ShortSaleThresholdIndicator: "N",
+				IpoFlag:                     " ",
+				LuldReferencePriceTier:      "2",
+				EtpFlag:                     "N",
+				MarketCategory:              MKTCTG_NYSE_AMERICAN,
+				FinancialStatusIndicator:    FSI_NOT_AVAILABLE,
+			},
+			want: []byte{82, 3, 81, 0, 0, 10, 55, 214, 144, 86, 87, 66, 72, 66, 32, 32, 32, 32, 32, 65, 32, 0, 0, 0, 100, 78, 67, 90, 32, 80, 78, 32, 50, 78, 0, 0, 0, 0, 78},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.s.Bytes(); !cmp.Equal(got, tt.want) {
+				t.Errorf("StockDirectory.Bytes() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}