diff --git a/mil_common/drivers/mil_usb_to_can/test/test_packets_sub9.py b/mil_common/drivers/mil_usb_to_can/test/test_packets_sub9.py
index 01c1dc47a..c58a8c32c 100755
--- a/mil_common/drivers/mil_usb_to_can/test/test_packets_sub9.py
+++ b/mil_common/drivers/mil_usb_to_can/test/test_packets_sub9.py
@@ -8,7 +8,7 @@
 
 
 @dataclass
-class TestPacket(Packet, msg_id=0x47, subclass_id=0x44, payload_format="BHf"):
+class TestPacket(Packet, msg_id=0x47, subclass_id=0x44, payload_format="?Hd"):
     example_bool: bool
     example_int: int
     example_float: float
@@ -23,7 +23,7 @@ def test_simple_packet(self):
         packet = TestPacket(False, 42, 3.14)
         self.assertEqual(packet.msg_id, 0x47)
         self.assertEqual(packet.subclass_id, 0x44)
-        self.assertEqual(packet.payload_format, "BHf")
+        self.assertEqual(packet.payload_format, "?Hd")
         self.assertEqual(packet.example_bool, False)
         self.assertEqual(packet.example_int, 42)
         self.assertEqual(packet.example_float, 3.14)
@@ -36,6 +36,13 @@ def test_assembled_packet(self):
         self.assertEqual(assembled[2], packet.msg_id)
         self.assertEqual(assembled[3], packet.subclass_id)
 
+    def test_format(self):
+        packet = TestPacket(False, 42, 3.14)
+        self.assertEqual(
+            TestPacket.from_bytes(TestPacket.__bytes__(packet)),
+            packet,
+        )
+
     def test_comparisons(self):
         packet = TestPacket(False, 42, 3.14)
         packet_two = TestPacket(False, 42, 3.14)