diff --git a/heat/engine/resources/openstack/neutron/port.py b/heat/engine/resources/openstack/neutron/port.py
index 641ad28883..0d31560e2a 100644
--- a/heat/engine/resources/openstack/neutron/port.py
+++ b/heat/engine/resources/openstack/neutron/port.py
@@ -245,7 +245,6 @@ class Port(neutron.NeutronResource):
             constraints=[
                 constraints.CustomConstraint('mac_addr')
             ],
-            update_allowed=True,
         ),
         ALLOWED_ADDRESS_PAIRS: properties.Schema(
             properties.Schema.LIST,
@@ -543,7 +542,6 @@ class Port(neutron.NeutronResource):
         result = super(Port, self).parse_live_resource_data(
             resource_properties, resource_data)
         result[self.QOS_POLICY] = resource_data.get('qos_policy_id')
-        result.pop(self.MAC_ADDRESS)
         fixed_ips = resource_data.get(self.FIXED_IPS) or []
         if fixed_ips:
             result.update({self.FIXED_IPS: []})
diff --git a/releasenotes/notes/port-mac-address-update-b377d23434e7b48a.yaml b/releasenotes/notes/port-mac-address-update-b377d23434e7b48a.yaml
new file mode 100644
index 0000000000..781fffde35
--- /dev/null
+++ b/releasenotes/notes/port-mac-address-update-b377d23434e7b48a.yaml
@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    ``OS::Neutron::Port`` resources will now be replaced when the
+    ``mac_address`` property is modified. Neutron is unable to update the MAC
+    address of a port once the port is in use.