diff --git a/selfdrive/car/interfaces.py b/selfdrive/car/interfaces.py
index 2ff26891ed..f0dae2d3f9 100644
--- a/selfdrive/car/interfaces.py
+++ b/selfdrive/car/interfaces.py
@@ -1,6 +1,6 @@
 import os
 import time
-from abc import abstractmethod
+from abc import abstractmethod, ABC
 from typing import Dict, Tuple, List
 
 from cereal import car
@@ -23,7 +23,7 @@ ACCEL_MIN = -3.5
 # generic car and radar interfaces
 
 
-class CarInterfaceBase():
+class CarInterfaceBase(ABC):
   def __init__(self, CP, CarController, CarState):
     self.CP = CP
     self.VM = VehicleModel(CP)
@@ -170,7 +170,7 @@ class CarInterfaceBase():
     return events
 
 
-class RadarInterfaceBase():
+class RadarInterfaceBase(ABC):
   def __init__(self, CP):
     self.pts = {}
     self.delay = 0
@@ -184,7 +184,7 @@ class RadarInterfaceBase():
     return ret
 
 
-class CarStateBase:
+class CarStateBase(ABC):
   def __init__(self, CP):
     self.CP = CP
     self.car_fingerprint = CP.carFingerprint
diff --git a/selfdrive/hardware/base.py b/selfdrive/hardware/base.py
index 06c86f0c26..d2bcce6a1c 100644
--- a/selfdrive/hardware/base.py
+++ b/selfdrive/hardware/base.py
@@ -1,9 +1,9 @@
-from abc import abstractmethod
+from abc import abstractmethod, ABC
 from collections import namedtuple
 
 ThermalConfig = namedtuple('ThermalConfig', ['cpu', 'gpu', 'mem', 'bat', 'ambient', 'pmic'])
 
-class HardwareBase:
+class HardwareBase(ABC):
   @staticmethod
   def get_cmdline():
     with open('/proc/cmdline') as f: