diff --git a/hooks/pci.py b/hooks/pci.py
index 0f24df8a..d52e10fa 100644
--- a/hooks/pci.py
+++ b/hooks/pci.py
@@ -155,6 +155,8 @@ class PCINetDevice(object):
         self.mac_address = None
         self.state = None
         self.sriov = False
+        self.sriov_totalvfs = None
+        self.sriov_numvfs = None
         self.update_attributes()
 
     def update_attributes(self):
@@ -186,6 +188,7 @@ class PCINetDevice(object):
                                    'device', 'sriov_numvfs')
             with open(sdevice, 'w') as sh:
                 sh.write(str(numvfs))
+            self.update_attributes()
 
 
 class PCINetDevices(object):
diff --git a/unit_tests/test_pci.py b/unit_tests/test_pci.py
index a5043b35..e8615639 100644
--- a/unit_tests/test_pci.py
+++ b/unit_tests/test_pci.py
@@ -178,6 +178,40 @@ class PCINetDeviceTest(CharmTestCase):
         self.assertEqual(
             pci.get_sysnet_interface('/sys/class/net/eth3'), 'eth3')
 
+    @patch('pci.get_sysnet_interfaces_and_macs')
+    def test_set_sriov_numvfs(self, mock_sysnet_ints):
+        mock_sysnet_ints.side_effect = [{
+            'interface': 'eth2',
+            'mac_address': 'a8:9d:21:cf:93:fc',
+            'pci_address': '0000:10:00.0',
+            'state': 'up',
+            'sriov': True,
+            'sriov_totalvfs': 7,
+            'sriov_numvfs': 0
+        }], [{
+            'interface': 'eth2',
+            'mac_address': 'a8:9d:21:cf:93:fc',
+            'pci_address': '0000:10:00.0',
+            'state': 'up',
+            'sriov': True,
+            'sriov_totalvfs': 7,
+            'sriov_numvfs': 4
+        }]
+        dev = pci.PCINetDevice('0000:10:00.0')
+        self.assertEqual('eth2', dev.interface_name)
+        self.assertTrue(dev.sriov)
+        self.assertEqual(7, dev.sriov_totalvfs)
+        self.assertEqual(0, dev.sriov_numvfs)
+
+        with patch_open() as (mock_open, mock_file):
+            dev.set_sriov_numvfs(4)
+            mock_open.assert_called_with(
+                '/sys/class/net/eth2/device/sriov_numvfs', 'w')
+            mock_file.write.assert_called_with("4")
+            self.assertTrue(dev.sriov)
+            self.assertEqual(7, dev.sriov_totalvfs)
+            self.assertEqual(4, dev.sriov_numvfs)
+
 
 class PCINetDevicesTest(CharmTestCase):