diff --git a/tests/test_mac_remove_association.py b/tests/test_mac_remove_association.py
new file mode 100644
index 0000000..f30575d
--- /dev/null
+++ b/tests/test_mac_remove_association.py
@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+#  Copyright (c) 2020 - 2026 netbox-sync team. All rights reserved.
+#
+#  netbox-sync.py
+#
+#  This work is licensed under the terms of the MIT license.
+#  For a copy, see file LICENSE.txt included in this
+#  repository or visit: <https://opensource.org/licenses/MIT>.
+
+"""Removing the interface association of a MAC address must unset it as primary MAC of the interface.
+
+NetBox (>= 4.2) refuses to unassign a MAC address which is still the primary MAC of its interface.
+"""
+
+from module.netbox.object_classes import NBInterface, NBMACAddress
+
+
+def test_remove_interface_association_unsets_primary_mac_of_the_interface(check_redfish_source):
+
+    context = check_redfish_source()
+    interface = context.inventory.add_object(
+        NBInterface, data={"name": "vmk0", "device": context.device, "type": "virtual"}, source=context.source)
+    mac_object = context.inventory.add_object(
+        NBMACAddress, data={"mac_address": "00:50:56:67:39:DA", "assigned_object_id": interface,
+                            "assigned_object_type": NBInterface}, source=context.source)
+    interface.update(data={"primary_mac_address": mac_object}, source=context.source)
+
+    mac_object.remove_interface_association()
+
+    assert "primary_mac_address" in interface.unset_items
+    assert "assigned_object_id" in mac_object.unset_items