diff --git a/mozc-nazoru/src/nazoru/led.py b/mozc-nazoru/src/nazoru/led.py
index 4dadcc7..fa44644 100644
--- a/mozc-nazoru/src/nazoru/led.py
+++ b/mozc-nazoru/src/nazoru/led.py
@@ -16,7 +16,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-class LEDBase():
+class LEDBase(object):
   def __init__(self, pin):
     self._pin = pin
   def on(self):
@@ -25,6 +25,8 @@ class LEDBase():
     pass
   def blink(self, interval):
     pass
+  def set_brightness(self, brightness):
+    pass
 
 try:
   import RPi.GPIO as GPIO
@@ -134,6 +136,9 @@ except ImportError as e:
 
   class LED(LEDBase):
     pass
+  class SlowLED(LEDBase):
+    def __init__(self, pin, delay_ms):
+      super(SlowLED, self).__init__(pin)
 
 LED_BLUE = LED(38)
 LED_RED = LED(40)