2 files changed, 24 insertions, 1 deletions

diff --git a/glucometerutils/support/freestyle.py b/glucometerutils/support/freestyle.py
index 1c5e284..816af81 100644
--- a/glucometerutils/support/freestyle.py
+++ b/glucometerutils/support/freestyle.py
@@ -28,7 +28,7 @@ from glucometerutils.support import hiddevice
 _INIT_SEQUENCE = (0x04, 0x05, 0x15, 0x01)
 
 _FREESTYLE_MESSAGE = construct.Struct(
-    'hid_report' / construct.Const(construct.Byte, 0),
+    'hid_report' / construct.Const(0, construct.Byte),
     'message_type' / construct.Byte,
     'command' / construct.Padded(
         63,  # command can only be up to 62 bytes, but one is used for length.
diff --git a/test/test_freestyle.py b/test/test_freestyle.py
new file mode 100644
index 0000000..0ff669d
--- /dev/null
+++ b/test/test_freestyle.py
@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+#
+# SPDX-License-Identifier: MIT
+"""Tests for the common FreeStyle functions.."""
+
+# pylint: disable=protected-access,missing-docstring
+
+from absl.testing import absltest
+
+from glucometerutils.support import freestyle
+
+
+class TestFreeStyle(absltest.TestCase):
+
+    def test_outgoing_command(self):
+        """Test the generation of a new outgoing message."""
+
+        self.assertEqual(
+            b'\0\x17\7command\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0'
+            b'\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0',
+            freestyle._FREESTYLE_MESSAGE.build(
+                {'message_type': 23, 'command': b'command'}),
+        )