diff --git a/ev3dev/core.py b/ev3dev/core.py
index e09b841..868ddd1 100644
--- a/ev3dev/core.py
+++ b/ev3dev/core.py
@@ -216,6 +216,10 @@ def __init__(self, port=None, name=SYSTEM_DEVICE_NAME_CONVENTION, **kwargs):
 
 
 # ~autogen
+
+    def __del__(self):
+        self.stop()
+
 # ~autogen generic-get-set classes.motor>currentClass
 
     @property
@@ -731,6 +735,10 @@ def __init__(self, port=None, name=SYSTEM_DEVICE_NAME_CONVENTION, **kwargs):
 
 
 # ~autogen
+
+    def __del__(self):
+        self.stop()
+
 # ~autogen generic-get-set classes.dcMotor>currentClass
 
     @property
@@ -962,6 +970,10 @@ def __init__(self, port=None, name=SYSTEM_DEVICE_NAME_CONVENTION, **kwargs):
 
 
 # ~autogen
+
+    def __del__(self):
+        self.float()
+
 # ~autogen generic-get-set classes.servoMotor>currentClass
 
     @property
diff --git a/tests/api_tests.py b/tests/api_tests.py
index 5a7458b..a60d202 100755
--- a/tests/api_tests.py
+++ b/tests/api_tests.py
@@ -28,6 +28,12 @@ def test_device(self):
         self.assertTrue(d.connected)
 
     def test_medium_motor(self):
+        def dummy(self):
+            pass
+
+        # Do not write motor.command on exit (so that fake tree stays intact)
+        ev3.MediumMotor.__del__ = dummy
+
         m = ev3.MediumMotor()
 
         self.assertTrue(m.connected);