diff --git a/qubes/vm/__init__.py b/qubes/vm/__init__.py
index e6ebbb3a..19ce16e7 100644
--- a/qubes/vm/__init__.py
+++ b/qubes/vm/__init__.py
@@ -68,6 +68,73 @@ class BaseVMMeta(qubes.plugins.Plugin, qubes.events.EmitterMeta):
         cls.__hooks__ = collections.defaultdict(list)
 
 
+class DeviceCollection(object):
+    '''Bag for devices.
+
+    Used as default value for :py:meth:`DeviceManager.__missing__` factory.
+
+    :param vm: VM for which we manage devices
+    :param class_: device class
+    '''
+
+    def __init__(self, vm, class_):
+        self._vm = vm
+        self._class = class_
+        self._set = set()
+
+
+    def attach(self, device):
+        '''Attach (add) device to domain.
+
+        :param str device: device identifier (format is class-dependent)
+        '''
+
+        if device in self:
+            raise KeyError(
+                'device {!r} of class {} already attached to {!r}'.format(
+                    device, self._class, self._vm))
+        self._vm.fire_event('device-pre-attached:{}'.format(self._class), device)
+        self._set.add(device)
+        self._vm.fire_event('device-attached:{}'.format(self._class), device)
+
+
+    def detach(self, device):
+        '''Detach (remove) device from domain.
+
+        :param str device: device identifier (format is class-dependent)
+        '''
+
+        if device not in self:
+            raise KeyError(
+                'device {!r} of class {} not attached to {!r}'.format(
+                    device, self._class, self._vm))
+        self._vm.fire_event('device-pre-detached:{}'.format(self._class), device)
+        self._set.remove(device)
+        self._vm.fire_event('device-detached:{}'.format(self._class), device)
+
+
+    def __iter__(self):
+        return iter(self._set)
+
+
+    def __contains__(self, item):
+        return item in self._set
+
+
+class DeviceManager(dict):
+    '''Device manager that hold all devices by their classess.
+
+    :param vm: VM for which we manage devices
+    '''
+
+    def __init__(self, vm):
+        super(DeviceManager, self).__init__()
+        self._vm = vm
+
+    def __missing__(self, key):
+        return DeviceCollection(self._vm, key)
+
+
 class BaseVM(qubes.PropertyHolder):
     '''Base class for all VMs
 
@@ -87,7 +154,7 @@ class BaseVM(qubes.PropertyHolder):
             tags={}, *args, **kwargs):
         self.app = app
         self.services = services
-        self.devices = collections.defaultdict(list) if devices is None else devices
+        self.devices = DeviceManager(self) if devices is None else devices
         self.tags = tags
 
         self.events_enabled = False
diff --git a/tests/vm.py b/tests/vm.py
index 3b66a491..f716b652 100644
--- a/tests/vm.py
+++ b/tests/vm.py
@@ -6,9 +6,92 @@ import unittest
 import lxml.etree
 
 sys.path.insert(0, '../')
+import qubes
+import qubes.events
 import qubes.vm
 
 
+class TestEmitter(qubes.events.Emitter):
+    def __init__(self):
+        super(TestEmitter, self).__init__()
+        self.device_pre_attached_fired = False
+        self.device_attached_fired = False
+        self.device_pre_detached_fired = False
+        self.device_detached_fired = False
+
+    @qubes.events.handler('device-pre-attached:testclass')
+    def on_device_pre_attached(self, event, dev):
+        self.device_pre_attached_fired = True
+
+    @qubes.events.handler('device-attached:testclass')
+    def on_device_attached(self, event, dev):
+        if self.device_pre_attached_fired:
+            self.device_attached_fired = True
+
+    @qubes.events.handler('device-pre-detached:testclass')
+    def on_device_pre_detached(self, event, dev):
+        if self.device_attached_fired:
+            self.device_pre_detached_fired = True
+
+    @qubes.events.handler('device-detached:testclass')
+    def on_device_detached(self, event, dev):
+        if self.device_pre_detached_fired:
+            self.device_detached_fired = True
+
+class TC_00_DeviceCollection(unittest.TestCase):
+    def setUp(self):
+        self.emitter = TestEmitter()
+        self.collection = qubes.vm.DeviceCollection(self.emitter, 'testclass')
+
+    def test_000_init(self):
+        self.assertFalse(self.collection._set)
+
+    def test_001_attach(self):
+        self.collection.attach('testdev')
+        self.assertTrue(self.emitter.device_pre_attached_fired)
+        self.assertTrue(self.emitter.device_attached_fired)
+        self.assertFalse(self.emitter.device_pre_detached_fired)
+        self.assertFalse(self.emitter.device_detached_fired)
+
+    def test_002_detach(self):
+        self.collection.attach('testdev')
+        self.collection.detach('testdev')
+        self.assertTrue(self.emitter.device_pre_attached_fired)
+        self.assertTrue(self.emitter.device_attached_fired)
+        self.assertTrue(self.emitter.device_pre_detached_fired)
+        self.assertTrue(self.emitter.device_detached_fired)
+
+    def test_010_empty_detach(self):
+        with self.assertRaises(LookupError):
+            self.collection.detach('testdev')
+
+    def test_011_double_attach(self):
+        self.collection.attach('testdev')
+
+        with self.assertRaises(LookupError):
+            self.collection.attach('testdev')
+
+    def test_012_double_detach(self):
+        self.collection.attach('testdev')
+        self.collection.detach('testdev')
+
+        with self.assertRaises(LookupError):
+            self.collection.detach('testdev')
+
+
+class TC_01_DeviceManager(unittest.TestCase):
+    def setUp(self):
+        self.emitter = TestEmitter()
+        self.manager = qubes.vm.DeviceManager(self.emitter)
+
+    def test_000_init(self):
+        self.assertEqual(self.manager, {})
+
+    def test_001_missing(self):
+        self.manager['testclass'].attach('testdev')
+        self.assertTrue(self.emitter.device_attached_fired)
+
+
 class TestVM(qubes.vm.BaseVM):
     qid = qubes.property('qid', type=int)
     name = qubes.property('name')
@@ -16,7 +99,7 @@ class TestVM(qubes.vm.BaseVM):
     testlabel = qubes.property('testlabel')
     defaultprop = qubes.property('defaultprop', default='defaultvalue')
 
-class TC_BaseVM(unittest.TestCase):
+class TC_10_BaseVM(unittest.TestCase):
     def setUp(self):
         self.xml = lxml.etree.XML('''
 <qubes version="3"> <!-- xmlns="https://qubes-os.org/QubesXML/1" -->