diff --git a/pingo/parts/button.py b/pingo/parts/button.py
index ddc362c..642baaa 100644
--- a/pingo/parts/button.py
+++ b/pingo/parts/button.py
@@ -1,3 +1,5 @@
+import pingo
+
 import time
 import threading
 
@@ -10,7 +12,7 @@ def __init__(self, pin):
         :param pin: A instance of DigitalPin
         """
         self.pin = pin
-        self.pin.mode = 'IN'
+        self.pin.mode = pingo.IN
         self.polling_task = None
         self._up_callback = lambda: None
         self._down_callback = lambda: None
@@ -56,10 +58,10 @@ def run(self):
         while self.active:
             current_state = self.switch.pin.state
             if current_state != last_state:
-                if current_state == 'HIGH':
+                if current_state == pingo.HIGH:
                     last_state = current_state
                     self.switch._up_callback()
-                elif current_state == 'LOW':
+                elif current_state == pingo.LOW:
                     last_state = current_state
                     self.switch._down_callback()
             time.sleep(0.05)
diff --git a/pingo/parts/test/test_switch.py b/pingo/parts/test/test_switch.py
index 085e433..f369a29 100644
--- a/pingo/parts/test/test_switch.py
+++ b/pingo/parts/test/test_switch.py
@@ -1,3 +1,4 @@
+import pingo
 import time
 import unittest
 
@@ -6,8 +7,8 @@
 
 class FakeDigitalPin(object):
     def __init__(self):
-        self.mode = 'IN'
-        self.state = 'LOW'
+        self.mode = pingo.IN
+        self.state = pingo.LOW
 
 
 class TestSwitch(unittest.TestCase):
@@ -23,11 +24,11 @@ def callback_down():
 
         self.my_switch.start()
         time.sleep(.1)
-        self.pin.state = 'HIGH'
+        self.pin.state = pingo.HIGH
         time.sleep(.1)
-        self.pin.state = 'LOW'
+        self.pin.state = pingo.LOW
         time.sleep(.1)
-        self.pin.state = 'HIGH'
+        self.pin.state = pingo.HIGH
         time.sleep(.1)
         self.my_switch.stop()
 
@@ -45,11 +46,11 @@ def callback_up():
 
         self.my_switch.start()
         time.sleep(.1)
-        self.pin.state = 'HIGH'
+        self.pin.state = pingo.HIGH
         time.sleep(.1)
-        self.pin.state = 'LOW'
+        self.pin.state = pingo.LOW
         time.sleep(.1)
-        self.pin.state = 'HIGH'
+        self.pin.state = pingo.HIGH
         time.sleep(.1)
 
         self.my_switch.stop()