diff --git a/j5/backends/hardware/j5/serial.py b/j5/backends/hardware/j5/serial.py
index 33b38079..5b955069 100644
--- a/j5/backends/hardware/j5/serial.py
+++ b/j5/backends/hardware/j5/serial.py
@@ -6,7 +6,7 @@
 from serial import Serial, SerialException, SerialTimeoutException
 from typing_extensions import Protocol
 
-from j5.backends import BackendMeta, CommunicationError
+from j5.backends import Backend, BackendMeta, CommunicationError
 from j5.boards import Board
 
 
@@ -43,7 +43,7 @@ def write(self, data: bytes) -> int:
         ...  # pragma: nocover
 
 
-class SerialHardwareBackend(metaclass=BackendMeta):
+class SerialHardwareBackend(Backend, metaclass=BackendMeta):
     """An abstract class for creating backends that use USB serial communication."""
 
     DEFAULT_TIMEOUT: timedelta = timedelta(milliseconds=250)
diff --git a/j5/backends/hardware/sb/arduino.py b/j5/backends/hardware/sb/arduino.py
index 6e5737cf..4507348e 100644
--- a/j5/backends/hardware/sb/arduino.py
+++ b/j5/backends/hardware/sb/arduino.py
@@ -71,7 +71,7 @@ def discover(
             boards.add(
                 SBArduinoBoard(
                     port.serial_number,
-                    cls(port.device, serial_class),  # type: ignore
+                    cls(port.device, serial_class),
                 ),
             )