diff --git a/xbee/txframe_test.go b/xbee/txframe_test.go
index a4d10ea..e03d7ca 100644
--- a/xbee/txframe_test.go
+++ b/xbee/txframe_test.go
@@ -19,6 +19,28 @@ func TestTxFrame_Bytes(t *testing.T) {
 		want   []byte
 	}{
 		// TODO: Add test cases.
+		{
+			name: "64 bit unicast",
+			fields: fields{
+				Id:          0x52,
+				Destination: 0x0013A20012345678,
+				BCastRadius: 0,
+				Options:     0,
+				Payload:     []byte{0x54, 0x78, 0x44, 0x61, 0x74, 0x61},
+			},
+			want: []byte{0x10, 0x52, 0x00, 0x13, 0xA2, 0x00, 0x12, 0x34, 0x56, 0x78, 0xFF, 0xFE, 0x00, 0x00, 0x54, 0x78, 0x44, 0x61, 0x74, 0x61},
+		},
+		{
+			name: "64 bit broadcast",
+			fields: fields{
+				Id:          0x00,
+				Destination: 0xFFFF,
+				BCastRadius: 1,
+				Options:     0,
+				Payload:     []byte{0x42, 0x72, 0x6F, 0x61, 0x64, 0x63, 0x61, 0x73, 0x74},
+			},
+			want: []byte{0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFE, 0x01, 0x00, 0x42, 0x72, 0x6F, 0x61, 0x64, 0x63, 0x61, 0x73, 0x74},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -46,7 +68,6 @@ func TestParseTxStatusFrame(t *testing.T) {
 		want    *TxStatusFrame
 		wantErr bool
 	}{
-		// TODO: Add test cases.
 		{
 			name: "wrong packet type",
 			args: args{